How do I let go of my ex?

Im such a bummer I keep asking questions about this but im so unhappy. How can I let my ex go he doesnt miss me hes moved on but I cant let go. I wake up with anxiety because hes gone. I think about him all day. He is so much happier without me and my daughter. We still cry everyday for him while hes out drinking and with girls. I have no friends and never go out to even meet any one. what is the best way to let go, he made it seem so easy :(