Coping with a cheater

Recently, I did took a peek at my boyfriend's phone. I know, it's an invasion of his privacy. But when his privacy involves a tinder notification, that's when I feel the need to jump in. I started snooping while he was asleep and found two dating apps, both of which had recent messages exchanged in them. Not wanting to stop there, I looked at his text messages and saw one conversation under a contact named "Sugar Mama". I read through the messages and they go all the way back to November. They've sent nudes back and forth. She's had him come over to have sex. He's asked her to give him head while he drives. 2 and a half damn years with this guy and this is what I get. I'm a complete and utter wreck and I can't cope with the amount of heartache I feel right now. I feel so broken and betrayed. I just don't know what to do. I need help.