How do I stop feeling guilty?

Be thankful that you have any feelings at all left after caregiving.
Guilt, anger, and other negative emotions can be used to motivate yourself, remind yourself, and to start taking care of yourself again.

Why are you guilty? Would it help to assign yourself a pennance?

Why, what have you done?

Say a Hail Mary, write a check, see
a therapist, turn yourself into the police...

A little more information would be helpful.