Finding the courage to leave

I’m in my second trimester and we have 2 kids together already. We were apart for a year and half and got back together, he proposed and things went just great.. around our daughters birthday I noticed a change in behavior and I caught him basically cheating. Sexting his ex and he probably stopped for a week and is doing it all over again. I seen she called him 6 times while he was at work and he works the night shift. Said it was because their son having nightmares and wetting the bed. But that’s a lie.. every time I try to ask questions or I see things she post online he gets defensive and tells me to leave or blocks me. We live together. And my heart is breaking every time. He said he would work on communication and would prove that he wanted to be with me and he’s sorry but that never happened. I have no where to go but I can’t stay here and I left my job because it was difficult to work but I’m not happy and it’s to toxic. I can’t tell my family because they’ll laugh and judge.