She wasn't trying to hurt you. It sounds like she was admitting her own failure and accepting blame because apparently she thinks that you could have done much better by yourself than you have.
Of course, everything is situational and I wasn't there to hear the tone of her voice or what was said before that remark. This may be her way of expressing disappointment in you, and if that is the case, you might be hurt or you might feel guilty, depending on how right you thought she was.
Parents do say things that hurt, whether they mean to or not. It wouldn't hurt if it was said by a stranger. You would just blow off a remark like that by thinking that they knew nothing about you and the choices you have made in your life.
I think that you should ask her for details about how you don't value yourself. Maybe you are engaging in some behavior that demonstrates low self-esteem and this may be the only words she has to express herself. If you can calmly find out what she really means and discuss it, maybe the two of you can experience some mutual understanding. None of us is perfect, moms or their adult kids. Maybe she has the wrong idea about you, maybe not. Maybe she really is trying to help and is just bad at parenting. You've known her for forty years, and vice versa. If you two have trouble communicating that is probably her fault, but placing blame won't solve the problem.