is he cheating?

So my boyfriend of exactly a year and five months recently had this girl add him on sc (snapchat). He told me he didn’t feel comfortable with her on sc and removed her right in front of my face. I found out that later on that day he added her back and told her he accidentally removed her. He asked her what she was doing on friday and she told him she’d be home alone but messages are obviously missing. He kept it from me till i seen it today. He’s just been really distant lately and hasn’t wanted much sex and he fucking loves sex. He didn’t even tell me goodnight, which sounds a bit dramatic, but we’ve never skipped telling each other goodnight. He left me on read actually but was texting the other girl all the way up till he fell asleep and didn’t bother to text me. They’re also texting in snaps which are pictures that disappear and can only be opened once pretty much. I have a strong intuition and it’s telling me he’s fucking cheating. He’s had a past of cheating in every one of his relationships and i only recently found that out. He’s cheated on me multiple times but my dumb ass stays. I swear i’m going to leave him in a heartbeat if i find out he’s cheating. I just can’t tell if i’m being crazy or not. I just need a hug right now. :(