My significant other for the last decades struggles with various mental disorders. What you describe reminds me of us. She never really managed to get proper therapy so far as well. We've learned some things the hard way, but we're happy and solid now.
For me at least what hit the hardest was not being trusted or being repeatedly accused of betrayal. This stuff seeps into my slightest cracks and blows up my own insecurities about inadequacy. It's a good thing you recognize these episodes. Could you just pull out of the situation when you feel one coming, request alone time? Defuse it, then come back to your loved one. That's what she does. I know to respect the alone time, no matter when it is needed. It's important for your partner to be aware of your struggles, but expecting them to accurately dismiss what you express on account of issues is not sustainable long term in my opinion. It's too hard to apply and too likely to backfire.
You're popular, amazing people have already crossed your path, there's no reason for it not to happen again. So prepare for making the next one the best one.