What would you do if your boyfriend has a baby and still "talks" to his mom ?

This is kinda confusing so i will try to keep it simple. Im 17 years old and in 12th grade and i just started dating this guy i like him a lot and he tells me how much he likes me all the time. He has a child. I understand that he has to talk to the mom a little but they text each other all of the time. He wants to see the child but she wont let him, but at the same time she comes up to me yelling at me like it is my fault that he does not see the baby. She is a two sided person. She also watches our every move and has people watching what we do. One day and im being 100% honest here he tapped me on the sholder and said hi (this was in the hallway) and we started talking while i was getting my books out of my locker within 5 mins she texed him and was like dont i matter anymore you dont say hi to me (he did not see her ) and u almost huged her . He did not, but even if he did we r going out what does it matter. She has a boyfriend too, she does not think we know though. She tell everybody things aout me some r not even true. I dont like to cause fights so i have been keeping my mouth shut ! What should i do i need advise!!!!!