Did you know I used to be promiscuous? Now I regret it.
How did you girlfriend at the time deal with that?
She dumped me when she found out I was promiscuous.
It's understandable to have regrets about your past behavior in regards to relationships. It's difficult to maintain a relationship if you are being promiscuous. It can be a sign that you aren't trustworthy enough to be in a relationship with just one person.
When my girlfriend dumped me, she told me it was because she wanted to focus on her education and she wanted to be with a guy that she could trust. That hurt, but I learned from it.
It's a tough lesson to learn, but you're a better man for it. Sometimes we have to goof up before our best selves can emerge.