warm welcome to pc, hazel.your hubby sounds emotionally abusive towards you and your daughter. it is not healthy for either of you to put up with this. for your daughter it can create low self esteem which she may never overcome. this sounds like he wants a power struggle to go on. BTW, abusive people have a common trait...many i'm sorrys after the verbal bashing (at u and yr daughter).
sounds like you've got multiple issues here. no one can decide for you re divorce.. as for an affair that just muddies the water. it also could be calamitous for you if hubby found out. just my opinion on this i'd recommend you not do it.
what i'd try first is a sit down discussion with hubby after the kids have gone to bed. see if you two can meet in the middle. be assertive and tell hubby how you feel. please keep us posted, hazel. we care about you.