Your whole story sounds horrible just devastating. Just because she didn't see your value, or treat you like you are valuable doesn't mean you don't have any. I'm going to be honest this bit -

"Told me I wasn't as intelligent as her because I didn't go to university, even though I was making good money and was part owner of a business, while she quit/was fired every few months. "

Is really shitty and struck a chord for me as well. I never knew how damaging it would be to hear that from someone. Or how fragile I was to judgement on my worth and value as a person. "Not being good enough for someone" I'm use to being judged and some judgement is fair, and some discomfort is good I'm human and have flaws, everyone has something they need to work on. I wonder if it's a regret of yours like it is mine. I should have been stronger and went to school. I just let people take it away from me, I gave up, I was weak. I can never erase that failure and even if I were to make good money I will still be judged. I've felt more insecure this year than I ever have. It's good in one hand because it's clearly something I need to fix, and work on. But holy shit I'd really like to feel worthwhile again.