Help with obesessing over ow

I have been divorced for a year now and I share a child with my exn so I have to keep in contact with him. I am finding it IMPOSSIBLE to shut off my feelings of wanting him, being jealous of ow and missing our family. I obsess over him and ow constantly. He cheated on me with her so they have been together a year or so now so it appears it is the real deal. I find I can't believe that this realtionship will end at some point. Feel as though she has "everything" he wants and then some and has the laid backness to allow him to just be "him" without questioning. she can just go back to her big home until he wants to play nice. It seems to be enough for her just to have him on her arm and keep doing for him without question. She has no job, lots of money and endless patience it seems. I see this NEVER ending. I need this justifiction that it wasn't just "me" and yes, can't lie here, I would love another chance with him. I would love for my daughter to have her family again. What can I do to stop obsessing over him and this ow because it is ruining my life on a daily basis and I am not finding the power within to stop it.
Thank you.