I’m sorry your dealing with this. It’s a scary situation.
I’ll just go ahead and ask ... Have you met face to face ? You say long distance but many people start out with just a online relationship which is fine, I met my husband online.
I’m going to type out what’s likely to be a unpopular opinion here. But I think it needs said.
You only have 3 months invested into this. She’s already disappeared once, she’s admitted she’s clingy but yet doesn’t stick around long ? When people tell you who they are it’s best to BELIEVE them.
I personal would cut my losses and find someone that you can physically be with, do things with.
I’m not saying 2 people with mental illness can’t make a relationship work, but at 3 months it should still be the happy “ honeymoon phase”
Good luck