boyfriend drama , should i tell him what i found out ?

[Hiccup]

This is going to be quite long i think...

Alrighty , i asked my boyfriend for his facebook password because personally i thought it was fair since he asked for mine a couple months back.I trusted him but i just wanted it to browse his news feed and stuff.I cheekly went onto his messages and there was only one message which was alright because it was a group chat with his music class.Anyway on facebook there is a search box in the messages section so i typed a few words like "I love you" etc to see all messages containing those words and i found PLENTY.For the past few hours i have looked at all of these messages start to end and came across something that caught my eye.Me and him have been dating for 4 months,we started on the 2nd September and this message was sent September 15th saying "Hey beautiful " . I also found a different message from another girl saying "where are you ? " sent on the 20th October 2013. this second message made me shake because the previous messages said "wanna fuck today etc" but the thing is from knowledge there has been no contact after the 20th October. My gut is telling me that they did meet up but what happened i have no clue.Reading the previous messages which happened during the beginning of the year , he asked her for sex and then they did it - i call this a sex buddy.

What do i do ? only reason im concerned is that why he met up with her during when we were going out.... the reason that there was one message is he deleted them all so i couldn't see it , hence the delay when he was giving me the password.

Im a person that doesnt start arguments so i really dont know what to say or do

[Nameless]

You really don't want to go through that, I'm telling you. Just break-up with him unless he has a very good reason.

[Ha! Funny Picture.]

This is a tough one. He might think you were prying and get offended. I would ask him who she was. If he cheated on you you have the right to know.

[Dylan]

Just break up with him without an explanation and make it sudden like when he thinks everything is fine. Then he'll be in shock and you'll get revenge.

[decentguy]

some guys are there who love to have multiple partners and they love all equally. they care for all and they do sex with all with love. there are some guys are love to have sex with many women but they just show love and care but they actually never do it. I think he is one of above types. so if you are ok with this and you have no issues if he does it with other girls in your absence then just do whatever you were doing.
but if you have issues with above then just tell him that you have found this accidentally and you don't want this from your soul mate. and tell him that you two can be friends but no soul mates any more. n with time make distance between you two.