Drunk bf possibly cheated

Hello lovely ladies. I’m lost on what to do. Part of me wants to stay but part of me wants to end things. So last night bf and I were suppose to play some video games but instead he did last minute plans to hang with his coworkers. I didn’t want to go so he got upset. Told him it was fine that he can go and hang out with them for a few hours and he’ll come home. So it’s 1am he calls letting me know he was on his way home it’s 230am and I called him asking him where he’s at. He’s telling someone to shush and it was a females voice he insisted it was his cousins that he swore but I didn’t want to believe it i hung up he didn’t text nor call me back until I called him at 7am he was huffing and puffing and grunting doing something that he was doing a job and that he’ll be home and the phone call ended 10min later nothing from him since then. He finally walks in through the doors at 10am!!!! I was livid I was pissed. Told him he should’ve been home by 130 but no at 10 told him I didnt believe what he had to say. He didn’t say anything about hanging with his “cousins” he told me he went to a house party and keep in mind we share our locations so I was looking at where he was so he went to 3 different houses and driving all over. I don’t know what he was doing. He said I’ve should’ve came and all this would’ve been prevented. I told him if I did this you would’ve been pissed packed your stuff and left me and never talk to me. He was also drunk. Me being the paranoid gf I go through his phone he obviously erased text msgs because in his phone log there was a girl name Sabrina supposedly his cousin but he called her at 945pm so I don’t know what to do. He’s passed out drunk I just want to lunch him so bad. I also have 2 beautiful girls there not his but he treats them like his own. Please help I just need to know what to do like I said before I’m lost.