Like SF is my last chance and I've wrecked it.
No. You are valued here. I know from me, but also others are happy you’re here. I don’t know what you could do to wreck things here, but I don’t think you would do that anyway, because you are just not the type of person who would do anything hurtful on purpose.
We, as humans, cannot avoid hurting the people around us. We care, and we also make mistakes. I see you beating yourself up. I can spot this because I do it too. Here’s an exercise that I learned a while back: List out 3 things you like about yourself. I know, it sounds corny as hell. It is, but that doesn’t mean it doesn’t work. It took me a few practice runs before I noticed any changes, but the point is to shift our attention from everything that is bad about us, over to what is better. Not necessarily fantastic, but just a little better.