crappy you have done an amazing thing for your son. He is struggling with his own family break-up and needs your compassion and TLC (that you obviously have in spades) focused on him not drained by some lying, toxic, loser who has already wrecking his own family. If you look at your son’s behaviour as a result of his emotional pain and seek ways to address that rather than looking it as just bad teenager behaviour that needs punishing you will have a much better outcome for you both. It’s v tough and as others have said it’s impossible to know what to do yourself so seek professional advice / support for parenting so that you don’t need to reinvent the wheel. In my experience this isn’t reading a few books but needs more active engagement either through a face to face support group or one on one or family counselling. You can make this all better for your son. As others have said, listen to him, reconsider what HE wants and needs through contact.
You have a lot on your plate right now / but you have achieved an awful lot. Split it out to separate tasks and focus on each in turn - try not to let one overwhelm the other.
Focus on your son, give him time, listen, support and give him what he needs emotionally. This will have a massive payback for you both.
Work hard at the NC. Each hour and day is a major success. Be proud of putting in the distance.
Get some counselling for YOU. I can see lots of co-dep behaviours in your posts, in your friendship as well as relationship behaviours and choices. This is a part of you that you need to attend to and change otherwise you will be back to square one.
Manage the house move - see if you and your son can do it positively as a team effort - give him some responsibility to plan and take action - a healthy strong boy will feel great taking apart furniture, packing etc and it will lighten your load.
Good luck - keep focused.
PS are you still in contact with ex by text? Or was that a typo?