At least you have been able to articulate that you struggle with caring about or loving yourself. It's definitely hard to have feelings for someone else in a healthy way when one doesn't even have their own sense of self worth. It's good that you have concern about hurting this woman. I think that you will have to sit with her and find a way to explain to her how you feel and you can do that where you emphasize that you care about her as a person but that you don't want her to commit to you in a way that isn't in her best interests. It sounds like this relationship was more of a friends with benefits relationship and not something where that was supposed to end up being a committed relationship where she would begin to expect more from you than you are capable of giving to her. Often these friends with benefits relationships are relationships that happen where both partners struggle with "selve love" and they have already broken off from a relationship that was not healthy or functioning for them.

You can impress on her that you are only being honest with her because you genuinely don't want to hurt or mislead her. Also, impress on her that it's not her lack of value either, but that you simply don't have your own sense of personal value and committing would be a mistake for both of you.