Well, for one thing, give up your night time job. You need to spend time with your kids, they are very angry children, and feel deeply hurt and abandoned by their Dad and by you. So, take a breath, and make a few jokes, things are getting heavy at your house. Have some fun with your children. Take them places just to be together and enjoy the day. They will give you a bad time, but you need to try to regain their trust and respect. Don't give up and don't yell.
One time a little girl in a class I was teaching, told me that she thought that I didn't like her because she was black. It surprised me so much that I got a tear in my eye and before I could say anything else, she saw the tear and said "never mind, I was wrong". Then she became a really close friend and got better grades and acted more relaxed in school. So there you go, love really helps. Lots of it.
Tell them how much you miss their Dad, and do things that Dad would do with them. I think that it is funny about the toilet paper on the ceiling, he probably saw some kids do that in the school bathroom. Stop making every thing a biiiiig deal, after all their lives have been split and hurt by their Dad having to be gone. Give them a break, and yourself too.
If you can get on their side, you will be the winner too, and so will they.
Good Luck, C. N.