Is my reason for full custody valid???

My children's father an I were in a 10 year relationship. In the end thing's ended up getting bad. He was physical, mentally, and verbally abusing me. He was charged in 2013 with assault against me. I was awarded a PFA for me and my children's. As the years have gone by he has been in and out of jail and I just recently had to get another PFA because of the threats and verbal abuse. We recently went to custody court and he promised me his new girlfriend would not be around the children because of her situation I feel its dangerous.( Her husband stabbed her to death in 2013 and they revived her while she held her 5 year old daughter.) My stupid ass agreed to 50/50 with no argument at all and he starts all over again. He has called CYS on me making false report's and now is keeping my children from me and I was told there os nothing I can do. Will a judge be in my favor with the situation of the new girlfriend??