It took me a long time to realise I wasn't always cheated on (sometimes repeatedly by the same person) because I was rubbish, but because I ignored early red flags the men in question were bad news and then didn't leave when it was painfully clear they were even worse news
Morning OP!
I just wanted to second the quote above.
It's very important (for everybody, all the time) to know how to listen to, and respond to their feelings, especially in relationships. People who had poor parenting (like you and I) naturally dismiss their own feelings, because, whilst they've been growing up, nobody gave a crap how they felt when their parents were beating each other up, or beating them up, or drinking themselves to oblivion, or whatever the poor parenting style was. The main thing that's going on at home was always something more important than how you felt, right? And now, suddenly, as an adult, the most important thing is how you feel. It's quite a flip. And it's hard to do because you more or less have to already have done it (ie care about your feelings enough) in order to make yourself care about your feelings!
That's why I asked you if you care about yourself, and tried to get you to see that you really do.
I went for years through rubbish relationships, biting my tongue, putting up with stuff I wasn't really happy with. Nothing dreadful (apart from one), but when I went to counselling, I got to the bottom of the problem: Everything I'd put up with made me have the same feeling, and it was the little tiny me, who didn't get looked after properly, screaming inside me 'YOU'RE NOT LISTENING TO ME!!!!'
Often, I hadn't even said what I felt, so, how anybody was supposed to listen to it, I don't know. But that's what stops rubbish and failing relationships. When they do something you don't like, you tell them. If they keep doing it, you leave them. I'll bet that in your relationships you have behaved in ways that you didn't like? Become a person you didn't want to be? That's what happens to people when their boundaries are pushed and pushed and pushed by something they find toxic.
I spent a lot of time here www.baggagereclaim.co.uk/the-blog/ whilst I was sorting my head out. I got quite bolshy 
Have a read and see if it helps.
Whilst you keep looking to others to validate you, you will never be happy, because nobody knows what you need like you do. You are an adult, and your primary job is to parent yourself , constantly, in a healthy way. Whatever your upbringing, you are no less able to do this than the most self respecting, dignified person you can think of. If you feel like you are less able, that's simply a perception. It's not a fact.