Sarah, it makes no difference what age someone is when you lose them. You still feel robbed. There is no fairness in life either. I lost my dad when I was 24. He was 75 and seemed very fit, but died after suffering a series of heart attacks over the space of a few months. I never knew my maternal granddad, who died at 52. My gran made it to 85, but had very bad health in old age and my mum made it to 96 despite having bad health all her life. In spite of that, she still made the most of her life and kept a very positive outlook and was determined to cling on for as long as she could. because she enjoyed her life. I also lost a school friend when she was only 16 to cancer and another to suicide in her early thirties, due to debilitating illness. Life is not fair. We just have to be grateful for however much time we had with the person we have lost, no matter how long or short a time that was. You say your mum had a good life and died peacefully and didn't get any of the nasty illnesses of old age, so that is a good thing. You had her for more that 40 years, so that's four decades of hopefully happy memories to treasure for the rest of your life. All we can do is be grateful for the time we did have with a lost loved one.
If there is one lesson that you learn after suffering a loss, it is who your friends are and who they are not. Stop wasting energy on this so-called 'friend' of yours. You have enough on your plate at the moment and don't need to waste your time worrying about him. He doesn't sound like he is worth your upset to me.
You don't need anyone's approval to feel however you do or to grieve however you want to grieve. There is no right or wrong way to grieve and no time-frame for how long that takes. In my experience, grief is something that is never gone, but dulls to an ache and a sadness in time, but is always there and always will be. Loss is a time of crisis when your 'friends' either step up or show they are not friends. Some may not know how to help, so they stay away thinking it is better to let you have some space, but others just say how sorry they are, then disappear back to their own lives and leave you to it. Unless they are helping you, best leave them behind and take care of yourself. If they really are friends, they will make the effort and invite you out for coffee or ring you for a chat, if not or they only criticize or say unkind things that make you feel worse, they're not your friend and not worth your time or energy.
My mum left me her house too. It's lovely that your mum thought you and your brother special enough to want to leave you her house. Again, in my experience, that can be a mixed blessing as it can involve you having to pay inheritance tax and fill in forms when you feel least able to cope with doing all that. Whatever items you inherit, that's a lovely gesture on your mum's part. It is not for others to denegrate and if your 'friend' has made a comment about it, then that speaks to me of jealousy and thoughtlessness. A house is still an object and although it has some monetary worth, if you had to choose between that and having your mum, I bet you'd choose your mum. At the end of day, we all go out of this world as we came into it, with nothing, and the thing we end up treasuring is the love we shared with those we have lost, not what objects they bequeathed to us. They may hold some sentimental value, but we would rather have the person who left them to us every time.
If you are managing to eat anything, you are doing well. There were days after I lost my mum when I forgot to eat or drink and couldn't be bothered to get dressed or to wash and just sat in a chair all day till it was dark and then went back to bed having done nothing. Whatever you eat, be it a biscuit, or a bar of chocolate, is fine. If you can manage something more wholesome, so much the better, but if you can't, don't worry about it. If the wine isn't helping, then stop drinking it and have a cup of tea instead.
As Karena says, I find it tends to make the misery worse, not better, so if you can resist it, that's probably a good idea.
You only have one mum, so I think it's inevitable that her loss will leave you broken-hearted, but you can do things that will help. I found it helped to put together an album of pictures of my mum and to write down in a diary each day how I was feeling and what I was thinking about. Some people start a memory book and recount tales of things they experienced with the person they have lost or they create a memory box and fill it with items that hold some special significance to that person. You just have to keep trying things until you find out what helps you and lean on those things until you feel stronger and you will, Sarah. It will take a while, but you will.
I did find it helped to revisit places I had gone to with mum. The memory of the times we spent there together made me smile, even if they also caused me to shed a tear or two, so why not do what your mum wanted you to do once you feel stronger and take that trip to somewhere nice. You'll be doing it for her and it will be the beginning of a store of new things to be able to tell her about, once you do meet again.
Your mum, like any mum, would want the best for you and now it's up to you to make that happen. You will never be who you were before you lost her and your life is now a blank page for you to begin to write. Getting used to life after a loss is a painful business and you are getting used to being a new you too, because loss changes you and how you see everything, which is probably why you are so angry with your friend. He hasn't lived up to your expectations, but that is probably a good thing in the end; better to find that out now so you can make a clean break of it, than to keep relying on him when he is probably only going to keep on letting you down.
I joined a class some time after my mum died. I needed something to get me out of the house, if only for a couple of hours a week and to distract me from my grief and give me something to look forward to and help me engage with life again. It helped that it was an activity that mum had enjoyed too in her younger day and that was the best thing I could have done. I made some lovely new friends there who have helped me more than any of my existing friends did and I still go now and it still helps.
You will find a way forward from this, Sarah, but you will need to do that yourself. No one is going to do it for you, so try to find those things that help you and don't rely on that to be others. No one helps you like you help yourself. Look for those things that help you feel better, look after yourself and when you feel up to it, make a plan for the the things you would like to achieve in life and be able to say you have done, then work towards that. Your mum would want that for you. You will always have her in your heart, so she will never really be gone from you and will always be your strength as you move into your future.