Struggling with a Friend's Mental Health Issues

I had an argument with a friend yesterday. They suffer from multiple mental health issues including being autistic. I’m a very supportive person and they are a wonderful, kind, funny human being but after years of their severe mental health issues grating on me and having to bite my tongue in half with what I can or cannot say or do in case it upsets them and letting them say what we should do especially after any disagreement/argument we had so we can keep the friendship going. The arguments we had I always kept my mouth shut about deeper rooted issues we have the we never fixed (their decision) now I’ve finally snapped at them bc they got funny with my over s trivial thing and I can’t keep doing this. I had to block them bc they would’nt leave me alone and we’d got into all the deep rooted issues (all based around their mental health) I feel like a horrible person bc I deeply struggle with my mental health but I’ve tried so hard for them for 6 years and I can’t keep doing this. I finally snapped and had enough and now they’re portraying me as “the bad guy” after years of trying my absolute hardest. Any thoughts or opinions???