Baby Mama Seeking My Bf Emotional Assurance!!

I have been dating my bf for two beautiful years. We are deeply in love with eachother. Problem? Baby mama! He was going out with her since high school and made two handsome sons. 9yrs old and 4yrs old. He came home one night and caught her on her cousins husband, kissing and grinding! (disgusting) Three years later we met and stayed in love ever since. Now, when I first met my bf sons they were amazing. But the 4yr old was still in daipers! Yes! daipers, and I was shocked! So as a woman and an aunty of two, I clearly took ignitiative to help my bf with his son to get him off the daipers. The mother has them on the weekdays, while we have them on the weekends. Meaning she has them for longer days! But when the mother brings him over, he is back in the daipers. Like as if it is more easier for her with him in the daipers! (Lazy b**ch) So i get mad! It takes two parents to help the child. But only my bf and I puts efforts into helping the boy get off the daipers! So months went by and finally she took hold and seen that we are helping him get off the daipers! (Gosh she is ignorant). Anyways, as I was bathing the 4yr old, he ended up having bumps on his butt, I mean a lot, from sitting in a soaked daiper when he is with his mother! Now im more pissed. These arenʻt even my kids and Iʻm pissed already! So my bf noticed that too awhile ago and kept bringing it up to the mother, she always yells and says " You know what that is already, i **cking told you!" So you clearly see her attitude. She constantly threatens my boyfriend that if he doesnʻt watch them for one more day, hence me and my bf works a fulltime job, she doesnʻt. She threatens him that he will never see his sons. She constantly tells him that they are moving to Guam and that shes taking his sons, etc. So, yesterday (Wednesday), she calls him and states that she made a doctors appointment for Friday and needs us to take my bf sons on Friday morning! But apparently we work! Also my bfs family works so we had no one too watch them for us. As we suggested, perhaps drop the kids off Saturday so we guarantee know that there is someone available to watch them, she flips and starts telling my bf that he will never see his sons, hes a good for nothing father, he doesnʻt do anything. I mean his baby mama constatnly puts him down when she doesnʻt get her way! Then that makes him heated up and all mad and I noticed that she is controlling him emotionally! So my bf asks "why do you always do this and make plans or make an appointment without planning ahead?" she shares what the doctors appointment was for and states "Its for my back pain, remember when you were with me i had the sharp back pain from the epidural!" (aka making my bf reminese). She tells him "**** you!" So my bf clearly told her "I donʻt care about your health, I just care about my sons!" She started crying! I mean, she couldnʻt stop calling him until he tells her "Ok, Ok I care about you!" As I am seating next to my bf telling his ex that he cares about her made me feel so eaten up inside! Like this **tch needs emotional assurance from my man! You clearly get a feel of this baby mama personality and how she rolls! I need help and advice about this irritating woman! Help me please!