My ex left me for someone online he met

It’s Been one month since he left. He said he needed space . I found a phone number from out of state and called it no answer. Confronted him and he said yeah a friend I met on poker. He did not want to sleep with me. So I told him to leave he did. He was already being distant. He didn’t want to make things work. He blamed me for everything that went wrong. He did things to make me mad. Then I checked phone bill he has been calling and her and she him . I begged him back several times. He acts smart. Called her number and told her he us married let us work it out. He got mad. At sons practice he would talk on the phone. I would be get mad and cry. So I stopped going . he only wants sex with me. I did 2 times. Everything I see him he acts mean I don’t understand why? Like I did something wrong? He walked out on us. I can’t believe it. I cry all the time by myself. He is sitting on the phone at his mom’s talking with no care. He has a picture of her on his phone. He says never met her in person. He sons says he is on the phone all the time..my son got mad and didn’t speak to him for a week . he calls late at night says he loves me misses us and is sorry. I don’t respond then he acts mean again. Wants me to spend the night. I don’t he gets mad cus he is paying my bills so thinks I should give him sex?? It’s been over two weeks since we had discussed sex. He wants to know who is pleasing me?
My question I want to call her and leave a message that he calls me sends me nasty pictures and wants sex . should I tell her??