**warning long problem**

I've been with SO for almost a year and we moved in a month after being together but we have known each other for ages. It was rocky at first but we are ended up working it out. I went out one day and a guy kissed me I told SO who went mad but we decided to work things out. Then a month later I read messages on his phone from his ex and other women. Turns out he was planning on meeting his ex gf and some other random girls I confronted him and he said sorry and that nothing happened. I shrugged it off and let it go since it was early days. It happened a few times when I caught him. Every time I confronted him he flipped it around on me and said I was going through his phone and invading his privacy. The final blow came when I discovered he had been texting girls again including his ex gf and on boxing day he lied he was at home when I was at work but he had been "chilling" with his friend I did not believe it. I needed more proof that he was being stupid behind my back. Finally last week he got ready for work as usual and left the house. He usually messages me when he is at work but he hadnt messaged me for hours. I got suspicious then rang his work to see if he was in and his colleague answered and said that he was not at work because he was off. I was fuming. I rang him and asked him where he was and he told me work that was enough. He came back home the next day I had packed my suitcase and demanded to know the truth. He denied cheating on me but his ex made it very clear that they had sex. I found messages from him telling her that he wants babies with her and he wants to be with her. He broke down and cried and he said he shouldn't have lied but he won't admit he cheated but we both know I'm not stupid. He said he wants to change because he doesn't like seeing me cry and be upset. This was a week ago. I told him it has been a year since we've been together either fix up or I'm done. I don't wanna end up like one of those women with a cheating husband lool. I gave him a last chance because I always give up in relationships but with him its different. He is actually trying. He doesn't use his WhatsApp as much neither his fb. He hasn't even topped up his phone. I am giving him a chance to change because I would want someone to give me a chance if I said I would change. Do you think I am being stupid or am I right in giving him a chance as he wants to fix things?.

Thanks guys.