I'm so sorry for your loss.
The memories of your loved one in pain are the worst, aren't they? I have found it helpful to get out old photographs and really concentrate on them and remember our life then. It makes me cry lots for what I have lost but it is gradually replacing those other awful images in my mind.
I know what you mean about not wanting to keep talking to friends and family. You feel, once you have told them something, you can't keep repeating it, even though you want to. I think maybe you must say things a couple of times so they understand how important the feelings are to you but, after that, it's possibly better to let your thoughts out somewhere like this, rather than in your friendships, unless they are people who have experienced bereavement themselves and will understand.
We need our friends and family to help us move forward with our new lives. I want to keep those relationships more about building a future than crying about the past. Don't know if that makes sense or if I'm explaining it properly.
I think it's very important to have support and to talk and let things out but it's also important to do it in a way that's comforting and appropriate for you. For some people that's family, for some it is friends, some people find counselling helps, some people write it all down. I talk to myself and read and write the posts here and that helps me.