My ex-wife brought my kids to me and said she can't handle them anymore. We signed a temporary custody letter and had it notarized because I couldn't afford attorney and she didn't want to go to court. She also gave me childsupport card. Now all of a sudden after my children have become settled, made new friends, and became accustomed to the life here, she has decided she wants to go by divorce papers, cancelled child support card and ordered a new one, does the notarized letter give me a leg to stand on?

Not much of one. Custody and support are the province of the courts. To be binding they need to be ratified by a court.

Will it help me when we go to court?

Depends on the court. The likelihood is it will not help much.

My children told her they don't want to live with her. Will the judge take that into consideration? The oldest is 11 and the middle is 9 and the youngest is almost 3

The court may listen, especially to the 11 yr old, but they don't have to put much weight on their preference.

You made a mistake by not going to court. You could have done it without an attorney.

She would not go to court with or without attorney

It was not up to her. You could have gone to court. If she refused to show up you could have won by default.

She probably didn't want a court because she knew she could change her mind.