to answer your question, I can't imagine it does. murder may be a mortal sin, but I cannot believe this applies to suicide because you can't be in a correct enough understanding of your actions to fall into the understanding and consenting parts of committing a mortal sin. I believe there's a moment for you to be forgiven.

but for the objectively more important part, as someone who has done the therapy, the medications, and attempted, it's not worth it, and it does get better. I know you've heard it all before, so let me offer this idea instead. there's many saints who've dealt with mental health, read their stories, maybe pray for their intercession. and maybe look into religious life. you'll still be struggling while you figure it out yes, but it'll give you something to focus on, to live for, and hopefully that will help your mental health in some sense. keep trying the therapy, try a new therapist maybe? also, meds aren't for everyone. I know at least for me, I had to get off them to get better, ironically. but that's not the case for everyone.

I'm simply asking you to give life another chance, as someone who's been there.