Relationship help!!!?

[Amanda]

ok, im not one to need advice nor help in my relationship because i know what i'm doing and i know how to react to most situations but now i'm just stuck. i've basically been in this very long, almost 5 year relationship with my "boyfriend" .. technically we're not together because it's always complicated and of course TRUST ISSUES! over the years, cheating on his behalf was always an issue, and yes i stayed. whatever anyways, i feel like i'm out of options right now because just yesterday i was on his phone, on twitter and i looked through his inbox and nothing was fishy.. everything was fine but when i went through his email i saw messages between him and a girl i know.. the conversation wasn't really a big deal but the point is.. if it wasn't such a big deal why would you have deleted it from your inbox to begin with? i asked him about it and first he lied about it, i told him there was no point in lying and then he confessed.. So now, you deleted the messages, lied about it, and if it wasn't a big deal WHYYY DELETE IT?? turned into a huge argument and I'm just so sick of the lies and stuff. i obviously don't trust him.. what should i do/say? i really want to take a real break and just kinda go our own ways so maybe he can just do whatever he wants and see what he wants because to be honest i dont even think its worth it anymore.