Undecided Question

Should i dump his ***?

I have been dating my bf for 8 months now. I found a way to get in is yahoo email account and found out that he has been talking to 8 other girls. From what i can tell in the conversations he has with them, he has never met them. But he tells them that he thinks they are beautiful and stuff like that. We live together and he never goes out alone. Oh, and he asked the girls for phone numbers so he could text them. Is this a form of cheating? I can't read what he says but i can see what they say. Read and tell me what you think.

Rebecca sent you a message.
Re: Hey

"hang out? lol how do we do that?"

Amanda sent you a message.
Re: Hey
"thats cool.. you think im pretty?? ha i dont"

Rebecca sent you a message.
Re: Hey

"(***)***-*** :) well lets see where
this goes then"

Nikki sent you a message.
Re: Hey
"so how many girlfriends do you have? there are alot in ur pictures. and how many random girls u found on facebook are you talking to other than me? no offence i just know how guys are"

Nikki sent you a message.
Re: Hey
"so since u cant get booty, ur not gonna talk to me?"

Amanda sent you a message.
Re: Hey
"well i dont really know you but I im getting to know you. ? its not that i dont think you are cute but beauty is only skin deep."