Let me understand, he's your husband or your partner? He broke up with you and got with someone else and now hes left her and wants to come back right?
Its going to take alot of time babe and you need to give yourself that time to decide.I dont think you can fake it (and you shouldnt even have to for his benefit he can sit and wait(. it will come naturally or it wont.
I'm feeling heartbroken tonight because now that hes back I dont think I can ever love him the same way again and thats a whole other thing accepting you might not even love the person you once loved so damn hard.
I think as women we try to rush through our feelings though as well. He left for a long time. He got on with life with someone else. Take your damn time too. You dont need to decide anything now. Let him earn his way back in