Is he cheating on me, should i let go, or do I wait around?

recently my hubby and i had a falling out and he moved in with a girl who claims is a friend she is 43 and he is 26 but she is known to like younger men. We have four kids and a four yr relationship. He is trying to stop his alcohol addiction and anger problem. Saturday he went to her house so her roommates boyfriend wouldnt try anything. he didnt come back. he umed i kicked him out and the next day her and him picked up the car and half of his clothes. he is still staying with the women and claims he sleeps on the sofa. He says he loves me, but he needs to think about US and how to become a better father/husband. I got this gut feeling he is with her. Do I let him just go or do I wait for him to decide if he is moving out perm or coming back. He IMs me everyday says he willalways love me. Saw the kids twice once for an hour and another time for 10mins. Says he was going back over there to sleep on the sofa. I dont understand. I need help. I asked if he wanted his other stuff/saidno