I need help!I'm having boyfriend problems AGAIN!!?

Okay so my boyfriend Kyle has a history of using girls for his advantages then dumping them,when i found out about this I confronted him but he told me that that was the past and that he'd never hurt/betray/use me,but Kyle is my first real boyfriend and I'm happy...all my friends don't trust him and think that I should leave him...I'm stuck in the middle and I don't know what to do! He tells me that I'm over-reacting and that I should trust him...is he right?