I don't think your questions were out of line at all. You have every right to be concerned for your child's welfare and that includes taking care of yourself.
There is nothing selfish about it, if you are not healthy you can't care for your child.
On the one hand I am sure that whilst on his meds he is absolutely fine. However he isn't, and ultimately this is about your sons welfare.

Don't be too hard on how long it took him to open up. From his point of view, he might have wanted to be sure this was the one. And it must be terrifying to share this kind of thing.
Questions, how invested are you?

My current partner has some quite serious issues, when he told me, I took the time to research what I could. Find a support group of partners in a similar situation. Then asked his permission to meet with his workers, go with him to his Dr, so I could ask my own questions, and see what I could do to maintain stability in the relationship.

You also have just escaped an abusive e past,are you ready not to bring your baggage into his environment, if you get my meaning. Survivors of abuse often have to Unlearn behaviours they learned with their abusers. They need to not be triggered by certain behaviours just because they relate them to a history of abuse.

All of this is a big ask,maybe some kind of therapy for yourself. Your son will react to you, if you are calm and secure in yourself, your son will feel safe.

I have 4 kids and similar back ground as you and so can definitely relate. My partner was equally forward and willing to do what ever I required to feel safe.

I wish you all the best,whatever you decide.