I signed the decree stating my two kids where living with my ex but since the divorce she has never had them they live with me and she didn't help me financially I'm worried about losing them if I try to change things but I believe she should help me

Did the decree specify visitation? I doubt if you can change primary custody, but you should be able to establish a visitation schedule.

To advise how to proceed we need to know what the decree said and how long ago it was issued.

If you have had the kids, the entire time, file for custody, go to court, prove it was you that had custody.

Remember if there was child support ordered, even if you have the kids, they can still make you pay the support to her, if that is what the order calls for

I'm sorry, I misread your question. Its up to you how to proceed. If she was awarded primary custody, but they have always lived with you, then you really should have the custody agreement modified.

If you have had the kids, the entire time, file for custody, go to court, prove it was you that had custody.

remember if there was child support ordered, even if you have the kids, they can still make you pay the support to her, if that is what the order calls for they do live with me and I do want to change the decree but everybody wants to charge 5000 dollars or more and yes I was ordered to pay child support , but she doesn't bother to see them I have to take them to her work so they can see her before our divorce I had just finish putting her through nursing school which now she is an registered nurse and is making 26 dollars an hour she has only given me about 160$ since aug and bought them some clothes maybe 300 $ worth she is always lying and breaking promises but I don't think her boyfriend and his two kids worry about anything cuase she pays for everything

Family court is less formal, so you may be able to get away without an attorney. You might try checking with local law schools, many have clinics that will help you prepare paperwork and strategy.