Boyfriend masturbating

Okay so I’m with my baby dad our child is now 6 months. My partner cheated when I was pregnant we worked through it. I don’t think he will do it again he regrets it and promised he don’t want to do it again so about7months after his working a lot as we need the money but at his day job his wanking??? Okay it’s normal for guys to do that as we don’t have much time as working a lot but it’s getting to me!! Seeing cum in his boxers when I do the washing I’ve told him it hurts me he said it’s a stress reliever I now bite me lips as Causes arguments that I’m paranoid and started checking his boxers 🤷🏻‍♀️... I don’t know how to get sex back on track should I just not care and see what happens? I even think of leaving him now but I want things to work I can’t be mad that his working right? What do I do 😩