Hm, I recognize this kind of thinking. This is alcohol talking. If I told you the amount of times my brain went off on obsessive and irrational tangents while drinking it would boggle your mind, I was the master of obsession while drinking and the drinking just fed it and made it super crazy. I quit drinking to get my head screwed on straight and it did that better than it helped anything else. Sobriety is the best for logical thinking and working through emotion rationally.
You're all wrapped up in the drama of your ex, you'd be shocked how quickly the obsession would dissipate if you got sober for good.