Which country has Jurisdiction?

My ex and I shared joint custody of our two sons. He had to needed to re-locate to Canada because his wife was deported. The judge allowed this motion after months of continue court hearings. When he lived in Canada for 6 months he cut off all contact. He refused to let me talk to see my children. While he was in Canada he opened a case and I was never notified. The judge sided with him and his motion for Sole cusrody and no access unless aggreed upon was the verdict. Its been nearly 3 years. His estranged wife messeged me on Facebook apologizing for alinenating the children from me and told me that they seperated and he moved back to the US. She had opened the case in Canada in fear of the children to gain full custody. I no longer live in the state he resides and is desperate on which order stands.