Absolutely ask your son. At that age, a lot of kids have very strong and very deep emotions on the issues surrounding them, but often adults underestimate their capacity to deal with these issues. He's already lived through a lot with you. He knows what it could be like - on both ends of the spectrum.
Another consideration if you give up guardianship, and decide not to see him because it is in his immediate best interests - would you have enough motivation to not suicide? It's a big and scary thought, but has to be a consideration. I know people whose parent's have suicided and those who have experienced parental severe mental illness (even if they weren't in that parent's care), and it has had much larger repercussions for long term mental health than the children seeing their parent while in severe mental illness.
Huge hugs. You really are an amazing person.