I agree that a disability shouldn't change anything. In fact, most people I know with disabilities would go out of their way to ensure that you do not feel sorry for them. But unfortunately there are a few out there who use it to their advantage
I had an ex who used his disability to wring every last bit of pity out of me. My ex had learned early on that by manipulating people's emotions with his disability, that he could get away with all sorts of bullshit.
It might not even be deliberate on your boyfriend's part. Sometimes disabilites can cause profound emotional problems along with the physical. Perhaps your ex's insecurities do have something to with his disability. If that is the case, it could be time for some serious therapy for him, with a specialist who works with people who have the same disability as he or maybe a cognitive therapist.
It's not your job to "fix" him. If you stay with this guy, I'm afraid you will end up sacrificing your happiness in order to constantly soothe his unstable ego. I think it might be good to let him go, and let him deal with his problems on his own. He sounds like an emotional vampire who is going to suck the life out of you.
“Inside every cynical person, there is a disappointed idealist”--George Carlin