Welcome Kissthestars.
Your post reminds me of how we can make their addiction the center of our universe, living in chaos as our "normal" state of being, and going crazy trying to stay one step ahead of the stealing and lies and disappointments.
My son is the addicted loved one in my life, but it was no different, my world became dark and sad and scary while living in his addiction.
You flunked out of school, you have been robbed by him, you have been afraid of him and now you see him cheating too. I'd say he has taken over your life too, but it doesn't have to be that way.
I don't think this is how you want to live, it's no life to be raising teenagers in.
It may hurt to leave, it may break your heart, but right now he is breaking your life and taking you down with him.
It's up to you whether you stay or leave, but just know that he is not likely to change anytime soon so if you want this to all end and if you want happiness and peace back in your life, the change will have to begin with you. You are stronger than you think and you can do it. Just believe in yourself and make your plan.
I'm glad you found us and hope you stick around.
Hugs