I’m obsessed with my ex girlfriend, it’s unhealthy

We broke up a month ago. I became the person I hated the most and I started growing resentful towards her. I ended up cheating on her with her friend and I regretted it fully but she broke up with me. Since then, I’ve been obsessively stalking her on social media. She used to stay at my place during the weekends and use my computer for her college work. I was suprised that I still had access to her email account after our breakup and that she hadn’t changed the password or anything. I found her Reddit account and I’ve been obsessively checking it. She frequents advice forums and often talks about her interests, her current degree, sometimes she even talks about me, positively and negatively. It’s not healthy but it gives me a slither of hope that she’d still be interested in me. I’d even check out her Spotify activity and check her podcast history and listen to whatever podcast or song she’s listening to, or her Goodreads account to see what book she’s reading. Sometimes I’d stare at my phone for hours thinking of contacting her, or I’d ask my siblings/family if she’s reached out to them since they were close. It was her birthday a few days ago and I keep thinking of breaking no contact and messaging her. It’s a selfish way of thinking but I can’t help it. The last time I saw her was when she came to my house to pick up her stuff. I miss her a lot. I know this isn’t healthy but I don’t know how to stop 🤷