What do I do?

I will try to keep this as short as possible. Yesterday my boyfriend was at work and we talked throughout the day and everything seemed great. He has his kids for the summer and also lives at his parents house because his ex gets 1700 a month for child support. I am currently 9 weeks pregnant with his baby. we are both stressed and tired. yesterday I was giving his son a bath and he went out to the garage and his mom followed him out there. for about an hour while I finished with the kids baths, they talked and I went out to let him know they were finished and he was crying. well little while later, he calls his ex and usually he lets me sit there and listen because she is crazy,  but this time he waved me away. so I waited and eventually went out and he hung up real fast. I had a very funny feeling but was just trying to let it go. to shorten it up. he had called her yesterday morning and had a heart to heart with her. then she had told him to call her later. he had told his mom he felt bad that he had had a heart to heart with her and told her a problem that we were having that I didn't even know was a problem. I guess what hurts is that he couldn't talk to me. he told the person that cheated on him a lot and in between having his 2 kids, had another kid, he constantly belittles him and takes him to court. and then when telling me everything he decides to tell me how great she was at always making sure he had a cooler full of drinks and food for work. I am at a loss. he told me I am just a good fuck buddy and good for watching his kids.