I need some judgement free advice and maybe just encouragement?

Okay, my husband and I have been married for three years! We just had a baby girl who is amazing and perfect. I have an amazing, sweet stepdaughter whom I love so much and she loves me the same. My husband cheated with the mother of his daughter during the first year of marriage... more than once. I left him but we eventually got back together and works things out. We're super strong and literally better than ever now. He finally saw what life would he like without me and that he couldn't make a life with his ex work because she's the opposite of me and she's not good for him. Like I said, my husband and I are doing beyond amazing. Well, the issue is I'm obsessed with looking at her social media. I even log into a friend's account to look at it. I just honestly hate her. She did so much to my marriage (I Know my husband did too, but she would come on to him and try to do sexual stuff with him at drop offs) and I just constantly obsess over her. I compare myself to her. She had a baby and didn't get stretch marks. I did. She lost her baby weight. I haven't. I just constantly have the urge to look at her social media. How can I stop being obsessed with her? Please don't bash me.

Edit: To Andi! Honestly, thank you so much. You truly have no idea what that means to me or how badly I needed to hear that. Thank you from the bottom of my heart.

Edit: To Jules! Thank you so much for sharing your story with me as well as some much needed kind words and advice. I sincerely appreciate it. It's so hard to not compare myself to her and social media makes it so easy to do because everything is just there. I truly appreciate you and you've made me feel so much better about everything.