You said your partner was supposed to be watching 1 year old, not you. He wasn’t watching her but then blaming you when she was unsupervised and you couldn’t find her.

Sure he loves his kids but he can’t ever handle them, according to you. They scream and cry and look frightened when he is alone with them etc You can be a loving parent but then be totally incompetent.

It’s understandable that you were looking for roots of your son’s problems in order to help him. You are his mother. We are responsible for helping and treating our children and we are responsible for getting them medical help etc That’s what mothers do, take care of their children. I don’t believe it’s the same with your partner. You aren’t this man’s mother, he is an adult. Poorly behaved adult.

If you believe MS causes these issues, I’d demand doctor providing the info on it. I’d not just assume. My husband has Tourette’s and OCD, he is neither abusive nor poorly behaved. If he started acting badly, id not just assume oh it must be Tourette’s. I’d be in a doctors office with him. It’s not enough to read that it might cause problems for people. That’s general information. It isn’t specific for your partner. Ton of people with MS are loving partners, not liars or abusers. It doesn’t apply to everyone.

It would have to be a requirement for him to stay with you: doctor appointment with specific explanation of his behaviors and treatments lined up. Same with perceived BPD. Diagnosis by a psychiatrist is needed to determine BPD, reading about it isn’t enough to diagnose people