Custody is twisted with lies... please help!!???

I have two children and one is 14 and the other 13. I gave custody to their father 3 years ago all of us were in agreement. Now the kids want to come home. I picked them up for the summer and my kids told me that the father was abusive and wanted me to hire a lawyer to get custody back. I did that, but the kids lied about it and they told the judge that my husband (step dad) that he d in front of them. The kids lied and now if I want custody then I have to pay for home study drug test for 1 year, back ground checks. The kids go to therapy once a week they told the therapist that they only want to come and live with me because their dad and stepmom fight over them all the time. I want to do what is best for my kids, he is a strict very strict dad and stepmom is the same. I do not see that as particulary bad, I see it as good, I only do not like them fighting over the kids. So now I am not sure what to do, If the parents were not fighting they would want to stay there.