Crazy Baby Momma

My boyfriend and I have been together for over 2 years now. He has a 3 yr old son with another woman. She is literally the most disrespectful bitch i have ever met!! She cannot get it through her thick skull that he is not going back to her!! She calls all the time talking about their past, why he is a better man now and he couldn't be the way he is with me, with her blah blah blah. He has went off on her countless times (he is not a mean person it takes A LOT to trigger him) and she stops for a while then right back to it! She is literally the crazy baby momma everyone warns you about! Ive about had it, but i don't want to lose my shit because of their son. I love that little man just like my own. I'm trying to be the bigger person but she makes it so hard! She refuses to get a boyfriend because shes stuck in la la land thinking were going to break up. She doesnt get it that hes not going anywhere!! I dont know how to keep my cool anymore. Im not a violent or disrespectful person but I'm about to show another side and i dont want to!! Has anyone else been through this??