Piece of shit ex

Hey girls,
A few months ago I left the guy I was dating and living with at the time because he got abusive, he wasn't treating me right and he was sneaking around doing stupid stuff. Well about a month ago, he messaged me and apologized and told me that he misses me - we started talking again and sort of made up. We started making plans to get married and to move in together and start fresh. We have talked every day since until today because I found out he's been sleeping with multiple women WHILE he's making plans to get married and move in with me. Yes, technically were both single but I didn't think I needed to put a label on our relationship since he obviously wanted to propose. Would you be upset or am I being over dramatic? Seems like I'm so blind when it comes to these situations because I love him so much and want to forgive him, but every women has their breaking point and I think I've hit mine. I'm so disgusted that he would talk to me all day and then hook up with other girls at night. Please help :(