Hello Rumar, I am sorry you are still finding all this so hard and painful.
I am glad your doctor is at least keeping an eye on you, but don't use the tablets if you are not confident that they will help. I had trouble sleeping too for months. I ended up taking Nytol sometimes to help me sleep and it did help, but there is a herbal version of it, so it did not have any bad side effects. Maybe you could try that instead.
I think everyone going through grief has a problem with sleeping. You can't switch your mind off and as you say, you have a tendency to keep going over everything that happened, but I am afraid that often does only lead to feelings of guilt and self-blame and just makes you more upset and makes it harder to sleep. Try not to go there. What you have to remember is that whatever you did at the time was the best you could do in the circumstances. It is very hard to know what to do at times of crisis, so we do the best we can with the information we have and just have to hope for the best, but it is unlikely anything you could have done would have changed the outcome. We can all find things to blame ourselves for when we go over what took place, but that doesn't mean we are right to blame ourselves. We did the best with what we had at the time. No one ever does less. You love the person in trouble so you make the choices that make sense at the time, but you still can not always do anything to prevent the worst from happening. There is no point to keep going over it and blaming yourself, Rumar. It isn't your fault.
Please try not to dwell on past losses either. Life unfortunately involves loss. No one lives forever. No one has their parents with them all their life usually either. I read somewhere that grief is the price we pay for love and loss is an unavoidable part of life. Try to focus on the many happy years you spent with your lost loved ones, not the end of their lives. That time only accounted for such a small proportion of their time and none of the legacy they have left you in the memories they helped create with you. Try to focus on that and realise that you have a treasure of happy memories to bolster you up into your future. Those will never be lost to you and the love you have for those you have lost will always be there too.
I don't think myself, that either the spirit dies or that love dies either. I think those we have lost may no longer be here in body, but that they still exist on another plane and that they still love us just as much where they are now. If you hold on to that thought, it may give you strength to realise that they would still want the best for us and want us to move forward with our lives, supported by the knowledge that they do still love us, even if they cannot be with us and knowing that, you know you owe it to them to try to make the best of this new phase of your life. You have to work on making it the best it can be because that is what they would want for you and it is up to you to do that for them now.
Try to have a plan to take tiny steps and achieve little goals each day. Maybe go into one of those rooms you are avoiding for a few minutes and just let yourself recall the good memories you have of the times spent in them. Pull back the curtains and let in the light. Dust the ornaments, put some flowers around and make the room look nice. Use the space. It belonged to both of you and is not something to be feared, but used to help you remember the good memories and stop you living with the bad ones that your mind is full of now. It may make you sad, because it is just you now, but it was yours and j's domain, so it will help you to live in that sphere, not in the sphere of nightmares, shut away in one room and locked inside your worst memories. I am sure J would want you to own your space and be proud of all the good memories he left you with.
Getting through this is going to need bravery and effort from you, Rumar. It has happened. You can't change it and you can't turn back the clock. All you can do is try to move forward one step at a time. You will fall down and have to keep getting up again, but you have to try and keep trying. Shutting yourself away won't make it so that this never happened. You have to look after yourself now, as I am sure J would want you to do. Let go of your guilt and accept the new reality, however unwanted. It is how it is now and you have to try to move forward. There is no way back, but you have a lovely path behind you. The path ahead is yours to choose and to navigate. Try to move off this bad path and onto a better one.
We are here for you. Sending you love and strength.