Don't tip toe round this abusive, selfish, arrogant prick !
Be yourself on holiday. If he then 'chooses' to continue to be a nasty prick to you, at least your parents will see exactly what he's like, so you won't need to explain things to them.
Plan on leaving and moving in with your parents short term, because it won't take you long to save enough for a deposit plus 1st months rent if you're living back with your parents.
Cancel any and all payments to joint account for 'bills'. Contact bank and ask to 'suspend' joint account until it can be closed properly.
Pack up. Take all kids stuff (toys/beds/clothes etc) and all your stuff, and everything you paid for (e.g TV's, furniture etc) because you'll need it to furnish your new house when you get one, even if it needs to go into storage short term. (Kids furniture etc must go with the kids, and not left at his house because the kids needs 'trump' making his life 'easier' by you leaving everything the kids need with him, and you being forced to buy all new stuff for them at your new house.)
Make sure you remove your name from all household bills etc asap and include current meter readings etc with a pic of the meter readings on the day you 'vacate' the property too. (You don't even need to tell him you've done this, as the gas/elec etc will send a 'To the occupier' letter to him so he can arrange to take over the supply etc)
Do a 'change of address' via post office for at least 6 mths, so that all your post will be redirected to your parents house automatically.
Put a claim in for child maintenance immediately, because he still has to pay for his bloody kids.
Put in a claim for any benefits you may be entitled to e.g Child Tax Credit etc and inform them of a 'change of circumstance' etc if you already claim.
Open a new email address and tell him that all child access etc will only be discussed via email, then block him on your phone/ SM etc.
It really won't take long to do all these things,(Ask work for emergency leave for a week or two or get GP sick note for stress) and you'll be free from his abuse. Free to start a new chapter with your DC which doesn't involve them watching their Mum being abused and treated like shit.