I am so sorry to read this update. You deserved so much better for mother's day and your kids deserve so much better from their father.
I agree with Pearl about seeing if S13 can talk to someone. Sometimes at that age they just need someone neutral and removed from the sitch to feel they can open up.
You have my ((hugs)) and prayers as you move forward with integrity and dignity and doing what is right for you and your kids. With all the support and strength you have I know you are going to be ok and help your kids to be ok.
