The first thing your friend needs to do is to admit that she has an impulse disorder, which means that she acts on her urges without considering the consequences. Being guilty for her behavior is a normal response, but it isn't going to help her resolve her problem. She needs to use the guilt as an impetus for change.
I recommend that she begin group therapy, which is a good place to resolve an impulse disorder since all kinds of feelings and urges are constantly being stirred up in a group setting. In therapy, she needs to figure out how and why she developed the problem in the first place. Was she raised by parents who allowed themselves to act on their angry or sexual urges? If so, she has patterned her behavior after them.
She will also need to learn to identify her feelings, talk about them, but not act them out. The process of learning to tolerate strong feelings and urges and not acting on them is the way to cure this problem. The self actually becomes stronger and stronger and more and more able to not act on impulse with time and practice.
So, my answer to your friend is simple. Use this slip as a growth experience, one that propels her to cure her impulse disorder once and for all. If she doesn't do this, her life will never be her own. She will forever be at the mercy of her urges and where they take her and her relationships will be destroyed one after another.
Your friend also needs to make sure that she doesn't have a drinking problem. Alcohol lowers a persons inhibitions and makes him/her more prone to acting on impulse. Combining alcohol with an impulse disorder is a lethal combination.
Let me know how my answer landed with your friend.