Hi Catherine628. You did the right thing, and you know you did. Having doubts in divorce/separation is normal. Any breakup of a marriage, even one with addiction and cheating, is sad and confusing for everyone involved. But give yourself some credit here! You did not 'take' the girls from their father - he bailed on them a long time ago with the choices he made. You are protecting them like you should as a responsible parent. Your girls will be okay because you are an awesome mom and you know it. You have to make sure you stay okay too for their sake.
My husband and I separated 6 weeks ago. He moved out. Our children are 4yrs and 8months. Things get a bit easier every day. Al-Anon has been my rock right now. I'll be thinking of you.