side girl?

what do you do when you’ve been talking to this boy for four and then find out you’re just the side girl? he’s always made me feel like we were exclusive but i just found from a coworker that he’s still together with his baby mama? when he first tried to get with me i asked if he was single or not and said no, he was done with the baby mama even though she was still trying to be with him. i just found out yesterday that they made one year!! what do i do? i feel so naive and stupid 😔😔 we’ve also been having unprotected sex multiple times and just recently i allowed him to cum in me (as i’ve been on birth control for two years already and i trusted him enough to do so) i just can’t believe i let myself to be played around like a doll 😭😭