I'm a shitty person ..

I don't know who else I can talk to so I'm posing this on here. I cheated on my boyfriend of a year about five months ago. My first serious boyfriend I was so very in love with him, then I went on a cruise and cheated on him. Obviously me and my ex had our issues , or else I wouldn't have done that. Anyways , we're now talking and deciding if we're gonna try again , but I couldn't help but hook up with someone last night. We're not dating really but I know he'd be upset knowing I slept with someone else. Idk why I keep doing this stupid shit and I feel like such a shitty person for it but it keeps happening. I love my ex but idk what to do :(