adultery

I have been in a friendship with one of my ex collegue from 2019,but suddenly in 2021 february or march we had some love conversation and sex chat.but i have never met him personally after marriage.i have shared my semi nudes photos,but he didnt except 1 photo showing his bare body.we have never spoke through phone or not even a video call.my husband has got to know about this.he even spoke to the guy and he even told we didnt met.but we planned to meet in future.the affair started from my side out of fun.i was not serious about the affair or nither i was planing to move out with him.but my husband did some domestic violence too with me,he inserted back side of a round brush inside my vagina and ass hole.still i was quiet as i was feeling guilty of disturbing my married life.he has the screenshot of the pics.now he has given option to leave but along with that he is kind of blackmailing me that he will send me behind the bars.now i am now one month pregnant with my husband only.but one important thing i got to know that he fucked my friend in my house only without her consent when she was fully unconscious after getting drunk and even he has given option that i and my daughter can stay with him if i plan a one night stand of him with my own sister in law,he had a desire of fucking her and as now i am caught for this extra marital affair he is showing it as revenge to fuck her.i am ready to give him divorce but if he doesn't and plans to file a adultery case on me.what should i do?but he keeps on going with different women all the time even after marriage.