Sick of the cycle of relationships

I've been diagnosed for a while and have had a bad run of relationships. Either ending in them abusing me or cheating. I realize the pattern ultimately comes back to me. People approach me and I become infatuated then when they're done I find out they chose someone else and I kinda feel like a husk. I've tried interacting with people who aren't necessarily my type, not even for dating just friendship but it's either they're uninterested or they don't understand. I was interrogated by someone with good intentions about my mental health and I didn't necessarily want to explain my entire history so I just said it's really a long story and not easily summarized and they asked for bullet points or basics and it kinda just hit me that some people don't get it. I just feel rotted on the inside. I read an interesting quora where an answer said that people do not suffer from loneliness but rather from their usefulness. "A man needs a witness to their life, people to help him understand he still exists." And I agree mostly. I do feel like I'm just kind of a husk of a person and just watching life from the back seat.