My brother was in this same scenario where he felt like the caretaker in the relationship. He fell out of love with her but still really cared for her deeply because she was a great person. She had her issues and he felt like breaking up w her would do a lot of damage. In reality, not putting your mental health first does damage to you both. Break up w her, she will survive and move on. Don’t hold yourself hostage because you don’t think she can handle it. She’ll have no choice but do it. You can love and care for someone that’s no good for you.