I caught my boyfriend cheating with his ex

Okay ..... I thought I had the perfect guy in my life.. we were meant for each other even families and friend were happy to see us together as a young couple, I'm a music teacher and programmer he's an engineer but work as a sever because is hard for him to get the job of his dream, I always encourage him to go to school to get a certification in order to get a better job so I was helping him with the food and payments... He  is Younger  than me for 3 years ... and been together for 1 year .. I found out that he was still having sex with his ex-girlfriend, I ask for an explanation and he just said he was not good for me that's all... and I was like OK thank you for being honest with me. What about the whole year we live together so you were lying to me saying that you love me all this time.  He says yes I love you but I'm no good for you I need to get my shit together I don't want to be a server anymore I want to get a better job want to be like you and blah blah blah and I said OK but this is why  you fuck your ex????? Wtf he's thinking ...... he didn't even try to fix anything with me .. I feel like he use me for his purpose.. how can we fall in love with somebody you think he's in the same page like you ????? It's been 2 months already and it's so hard not to be with him...