Hi, could you not try Family Mediation [not sure if that's the correct term], try ringing the citizens advice to see if it's available in your area. My kids often don't want to see their Dad....although he is not overtly abusive we have had problems with him 'siding' with his new family, especially over my daughter. My son is 16 now and only sees his dad when he wants to....not very often!
FM involves you ALL sitting with a counsellor to discuss your problems....maybe a little hard for your girls as they are young and may feel intimadated....but I'd give it a try!
Lisa x