Boyfriend messaging another guy for sex

[NorthLondonLad]

The question you have to ask yourself is: Are you Happy in this relationship, Will you ever be Happy in this relationship. Think about that word Happy and everything you need to make you Happy. If your partnership doesn't tick the boxes - then you need to leave him.

Everyone deserves happiness

[Tropx]

This is my first post in any forum so I am pretty unsure what to expect but all opinions welcome! Anyway a bit of background info, me and my boyfriend have been dating for about 3 months, I am 22 and he is 25. At the start of the relationship he told me was still in love with his ex who lives in a different city but would never go back to them, he also told me he cheated on that ex once when he was drunk but regretted it. I have been in previous relationships where I have been cheated on so I have a pretty general idea of what the warning signs are, so about a week ago him and his friend went to town on a saturday night and at 5:30 I receive a drunk message from him that said "love you" at the end, its the first time he ever has said it and I am not at that stage so I didn't say it back as I didn't think to much of him saying it in a text this early in the relationship whilst being drunk. We were meant to catch up on the Sunday but he said he needed time for himself and ignored my calls and messages the whole day.
During the week he was a bit distant and less intimate, and so I suspected something was up. When he went to have a shower he left his phone open on his messages and I looked (something I never do) but I saw a message from a guy who said he used to see before me and was dated from sunday (the day he was ignoring me). I opened it up and I found a lot of messages about them organising to meet up for very specific sex, he said that we were only dating but he wasn't opposed to sleeping with other people (he told me we were exclusively dating). The messages also including naked pictures being exchanged and how they were meeting up but ended because the other persons parents came home so my boyfriend couldn't go over. The whole day all I could think of was the messages so I confronted him about it and he apologised and said he wanted to continue the relationship and he would have never slept with the other person or would never cheat on me.
I reluctantly accepted his apology but it is still on my mind all the time, I have lost all my trust in him and I don't know if I could trust him again. After all it seemed pretty clear that if the other guy had the house to himself my boyfriend would have gone around there in a heartbeat, and the way he was talking dirty to the other guy made him sound like a sex addict.

Some of the messages he sent to the other guy:
I wish we had a car so we could at least give each other a hand or abit of mouth
Maybe you could help get me loose
Haha I would like to put you over a lounge or a chair and do you! Are your parents home now?
If I you had a car or I had one we could just do stuff in it rather than find a time when the houses are ready and empty

I would like to know what people's opinions are, am I overreacting? Should I stay with him or dump him?

Hmm can people change? He has cheated previously; unfortunately I find once a cheater, always a cheater past, present and future.

[TomStatic]

I think you are better off with him dude, he seams like abit of player from what u said by the messages , id say leave him before anything gets more serious and u get hurt badly