Bf is accusing me of cheating

I’ve been with my boyfriend (2 years on Oct. 27). We have one beautiful baby girl together.

But.... Within the first year of us being together. He started to accuse me of cheating on him and come to find out he had Been cheating on me with a girl we worked with. He’s starting to accuse me of cheating on him again, and Im really wondering if he’s not the one cheating again.. I’m not really sure what to do...