To stop contact New Years

[SSDDagain88]

So back story EX DH took me to court 3 years ago to have set access to 2 x DS and despite him having a solicitor and me self representing he walked away with less than he started as the judge stated he didn’t do day to day care so couldn’t just have holidays/ birthdays.
oct I asked what he wanted boys for Xmas as order is 24 hours between Xmas Eve and Boxing Day - he stated he would get them Boxing Day morning as wasn’t messing around to collect them during day on Xmas, all fine so we made plans. Day before Xmas Eve he messaged to say he would collect Xmas day at 3pm as that’s what we agreed so I screenshot messages of him saying Boxing Day and we had now made plans so it was Boxing Day, he wasn’t happy as said his plans had now changed but I stated that’s what was agreed in Oct. Demanded boys early Boxing Day (9.00am) and then turned up at 10.15am.
I messaged last night and said obviously boys back at 10.00am tomorrow can they remember coats to be told he wasn’t bringing them back until 8.00pm. I explained per the court order that’s not how it worked and if he wanted them longer he could of spoken to me and arranged it. He has now decided to ignore me and not return them.
he is meant to have them New Year’s Eve but I am now reluctant to let them go and am going to file with court regarding this breech (not the first). Both DS have been messaging me bored as he lives in a tiny bed sit and my autistic 9 year old struggles with no space or being able to have quiet space and he didn’t take them out at all yesterday or even do presents with them.
so is it unreasonable to keep them new year following this?

I wouldn't start playing tit for tat as that could go against you (I totally get your reasons) He's probably game playing so you need to cover yourself.
I would look at getting an urgent court hearing if possible as he's broken the court order and say he's refusing to bring them home. Keep the messages your children are sending stating that they're bored/struggling etc as evidence.

he is also ordered to do half the sick days when off school etc but in 3 years have never done one despite both DS having strep A earlier in the month and being ill
during the year- he is always too busy despite not working or anything at all

No. Don't do that. As pp said, tit for tat is the way madness lies. Return to court next year if you feel so strongly about it.

You need to document everything and take it back to court.
If he doesn't return them tonight as promised then I would get advice and seek an urgent ex parte court hearing.
A residency order in your favour would be a good idea if he's playing around over returning them. It would give you powers to enforce their return.