Need some advice please!?

Ok so at the start of the relationship with my boyfriend ( 9 years ago ) I slept with another man behind my boyfriends back, anyway that was at the very start but I’ve been faithful to him ever since, anyway, I found out in June last year that my boyfriend had a fling with some other women, he says they are not talking anymore, he says he hasn’t got her number anymore and she hasn’t got his number, he’s at work every day which is good but he’s always out on the weekend aswell, when he’s not at work! Am I rite to believe that something is still going on with her and him??he said he did it with her for revenge on me but I think he did out because he has no respect for me