Cheating Options

[LilBrunette0313]

Me and my boyfriend have been back together for about 3 months and the other day this girl calls me telling me that he's been calling her and trying to get together, but when I asked him about it he swore to me that she was lying. The reason I'm having such a hard time deciding who I believe is because he has cheated on me once in the past but we've both changed alot and hadn't had any problems, not even a fight until this happened. His mother even called me telling me it was a lie and even cussed the girl who told me this out. He swears he learned his lesson last time and wouldn't do it again but should I believe him? Please help me out!