It's potentially awful, really. He told me his gf was pregnant on Xmas eve (many years ago...). Then tried to shag me... I used to drive kids down to his on Xmas day then drive 25 miles home in tears... Then there was the Xmas I dropped the DCs off, watched them open over-expensive presents I could never afford, that they had to keep at his house.... Then the kids phoned in tears on Boxing Day because their dad & OW2 were too hungover to get out of bed and they hadn't eaten. I went to get them next day (couldn't drive due to tonsillitis meds and feeling shit and couldn't afford a taxi...) & the house was a bomb site, ex and OW2 still in bed and he wasn't 'allowed' to see them for 6 months after that....
...and now that OW2 has left and taken their DD abroad, he'll be alone at Xmas, probably in a fragile mental state and it's probably easier to keep an eye on him when he's here... But he better be on his absolute best behaviour or I'll stab the fucker. Metaphorically.
DCs are all delighted and I'll have to weather January being full of 'I miss daaaaaaaaaaad' s.