How do you let go of a grudge? It's becoming exhausting at this point but I just can't stop.

I'm going to try to make a long story short. My boyfriend and I broke up in March of 2017. He had been talking to this girl after me and him had an argument and I told him I wasn't sure if I could be with him anymore. He groomed this girl into liking him and broke up with me and used the crap out of this girl to pay his Bill's and what not. But this girl was using him too because she didn't want to live at home anymore. The whole situation was messy and screwed up. I found out that I was pregnant, and I was honestly very very harsh to my then ex. I called him every name under the sun and pushed him so far away. I was angry and hurt that he had moved on with some other girl so quickly as if I was nothing. But at that point I didnt know what was going on.

He had a lot of issues within himself. He began going to counseling and working on himself. He didn't talk to me for the first 4 months of my pregnancy and during that time he was in therapy to work on issues. Through his therapy he did a lot of soul searching and fixed himself and began to repair relationships. He and this girl parted ways, he made amends with his brother who he hadn't talked to in years and me and him began talking again. (We didn't end up getting back together for another 4 months.)

But anyways, we have fought, talked and cried and got to a great place together. Me and him are better than ever now. We communicate with each other, we respect one another and we show each other love. However, for some reason I hold a grudge against this girl. Every now and again I check on her social media and hope to see that shes doing terrible in life. I know its petty, childish or whatever you'd like to call it. I know it is.

I wont say it's all her fault that my boyfriend and I had broken up because it's not. It has a lot to do with him and myself. However, she knew we were together, lived together. Yet she chose to reach out to him, text him, entertain him fully knowing we were together. Hes no better than her but I despise this girl. I cant help but think had she not entertained him we could have done the counseling together. We wouldn't of had to split and fight and argue. He wouldn't have missed the first ultrasounds, hearing the heart beat, finding out the gender. I feel like she took so much from me. I literally just hate this girl and wish nothing but horrible terrible karma for her.