I'm falling apart!!!

So my ex and I broke up 9 months ago because I caught him cheating. come to find out the person he was cheating with is his best friends wife. The best friend died in January of this year. My ex and I were together for 4 years. Since then I see him every once in a while when he just decides to pop up. These 2 are trying their hardest to keep this a secret. They deny it to this day. There have been people who have seen them around town. This whore for lack of a better word found out I had his number and she changed the. number again. That won't change the fact that he still knows my number and will eventually call again. She is so insecure it's ridiculous. It's like she's trying so hard to make my life hell and make sure he stays by her side. Well little does she know he's already cheated on her with me. My son misses him so much and talks about him constantly. I still love him and I'm still in love with him. I have tried everything to stop feeling this way but I can't. I just feel like a piece of me dies everyday. I have all these emotions I'm feeling of anger, hurt,betrayal. My family was just ripped apart and I feel like I want to run to the in laws and let them know what's going on. Karma just takes too long.