In need of guidance

I messed up. I’ve been single now for two months but that doesn’t really matter. I’ve been complaining about obvious lack in a department and have been wanting to just do a hookup and I have never done one. I’ve had sex with two people both I’ve had a relationship with. So it’s my birthday and I’m 22 and the first time I have gotten drunkish (I’m drunk but not drunk drunk where I act like Snooki) but my friends are drunk and we go back to my house. I’m stress eating cause they are loud and I’m worried about my bitchy neighbor. So things die down and I go upstairs to out my bag away and go help clean up well my one friend who has a girlfriend comes up and is like can you keep a secret and starts to kiss me I push him off and ask about his girl and he’s like nah it’s not like that and we slowly go back to kissing and basically I slept with him and I feel really relieved cause I needed it but so shitty because I’m a bad person for doing it. I kept asking about his girl and I still did it. I feel like shit cause my dad cheats on my mom all the time and I hate it but now I’m the home wrecker I’m shit