Would I have a chance in court to get the current order changed?

My ex and I have joint legal and physical custody of our two sons. However, he is currently in jail awaiting sentencing for leading police on a high speed chase. He has quite a wrap sheet and has been in and out of jail for about a year now. He possessed weapons and even has videos and pictures of himself loading and showing off his guns on Facebook. He has no residence and lives in his car and stays in hotels. He is abusing drugs and has been in trouble for selling them as well. He is supposed to have them one week and then I have them another week per the court’s decision last year. However, this happened only for about 2-3 months and I have had them the rest of the time. I am their primary caretaker and they see him every few months when he pops back up and wants to see them, usually between jail stays. I want to file for full custody of them because I pretty much have it anyways, however I know if he was not in jail he would show up and fight me for custody like he did last time. I feel my kids are in danger when they are with him and it is not in their best interest to be around him unsupervised. Would he be brought to court from jail to try and fight it?