If their Dad walked out just before Christmas, then that must have been crap for them and 12-15, as they was then, is a really difficult development stage.
""Book a remote cottage / youth hostel next year make sure no tv, ps4 but board games. Don't tell them""
They will all be young men, they should be consulted on how they want to spend their time.
OP, I'm widowed, my youngest is 18, it's really struck me how I'm making my life about my GD.
It's not for everyone but I've joined in line dating, I'm looking at voluntary work, because it's so difficult to make friends as you get older.
You've got to build a life for yourself and not expect your Sons to provide it.
I'm close to my girls, now, but had some horrendous times during the teen years.
Me and my youngest share a love of Horror films, but she's wanted to stay up late on her laptop, so we've only watched one up to now.
She's a young adult, off collage, so it's about mutual respect.
Plan your Christmas next year and don't rely on others.