Welcome here, this is as it says a support forum and you are welcome to talk about anything as often as you like. And now is the exact time you need support. Major depression, self harm and suicidal thoughts all show how badly you are affected and how important it is not to have to try to endure them in isolation.
Sadly you have several things that have harmed you. The loss of someone you love, the doubts and self-blame over his trying to take his life, and the reaction both of himself and his family afterwards. Add to that trauma - the shock of entering that garage and finding him there.
Dealing with each of those things is a long process and as Sophie_M had told you Beyond Blue does deal a lot to about the subject starting with our 24/7 counseling service link plus
and pages leading from there.
For me to be blamed would be the worst thing. It is only natural to wonder about one's own actions and if they in some way contributed. To have others say it too is terible. Even if you had been having an argument, which often happens, that is a normal part of life and is simply something people sort out.
Blame, by self or others is always completely unjustified
People take their own lives or try to, and the reasons are within themselves, not with you or others. When bound up with all those other things it may take a long time to see in perspective, but it does come
Trying to deal with it all in isolation, his family rejecting you rather than comforting you, and his reaction too are things you, if you are like me, would need professional help to cope with. It's important and in no way a reflection on you to need that help, so see what our 24/7 help line given above by Sophie suggests.
Your physical reactions to the cold, to getting out the shower and everything else are to be expected and again will require time and professional help to get over. Even a death from natural causes , such as that of my wife, left me for a very long time with not wanting to repeat what I was doing at the time, not wanting to go near the hospital or smell and noise of the place
To start with I did not want to listen to those who tried to comfort, it was sort of meaningless. Eventually I did listen and came to see the care -even if clumsy- that was present
Do you have anyone , family or friend perhaps, to lean on and share your greif?