Kindly treat me with kindness.

F(30) m(29) I need some advice. I've been in a relationship with this person for several years. He cheated on me once, we reconciled, then he left me during a holiday. Eleven months later we got back together, but he cheated again and returned afterward. Things have been okay, but for the past month, we’ve been arguing non-stop. For context, I recently started a new job, and one of the people he cheated with is a colleague of his. I’ve struggled to move past that because he promised he stopped communicating with her, but I recently found a text exchange where he was still being friendly with her. Although it's been a few months since that incident, I still can't fully trust him; he often hides his phone. He mostly takes pictures of just our child or just him and our child, excluding me from a lot of moments. He also tends to place blame on me, and I feel so lost. This is my first serious relationship and my first heartbreak—any advice would be greatly appreciated.