How do I confront my husband

I have been with my husband for 4 years. I have two step sons, 13 and 15. They would come over for holidays and during the summer. I love them. Even though they can be a lot and are teens so they can be disrespectful i do love them. They stopped coming around more and this summer my husband said the boys didn't want to come down. Over the last couple years I noticed my husband almost avoid talking to them. They would call and he would just let the phone ring. I would tell him to answer it and he would say he will call them back but never does. They would call me looking for their dad and my husband would tell me to tell them he isn't here. My oldest step son turns 16 the 13th of this month and my husband forgot. I told him we need to get him something even if it's just sending him money. I tried to reach out to ask what he wanted for his birthday just to find out my step son blocked me. I asked my husband why he would do this and my husband didn't seem to care. He said it's probably their mother or the boys having an attitude. Idk why. I didn't like his answer and got a feeling in my stomach. I never go through his phone but something told me to do it this time. I went and found the conversations between his ex wife and some between his boys were he said that I am the one who doesn't want the boys over for the summer. And said he can't send a birthday present because he had $1000 to give his son for his 16th but I gambled it away. I haven't been to the casino in over a year. He has been telling them that I don't want the kids over and lying on me to his kids and ex wife. I have been so angry and want to confront him but idk how