Keep coming back as much as you need! I've been in your position, your self esteem is low and he knows it. You want him to want you. You want him to say he's so sorry and it will all be a mistake. Once you take a stand he starts to grovel and you try to fight it. You know what others are saying are right, but it's the little niggling voice of what if so you relent and you tell him you love him and you don't want this situation then he knows he's won.
This happened to me before and I learnt the hard way. Your self worth and your children are worth more than what he is doing to you. Please don't let him hurt you anymore. It's hard, I know. One minute or hour or hour or day your ok then it all falls to pieces.
Turn the tables, he's feeding of your low self esteem. He wants you to want him and when you don't he runs back, then when he gets his way he's happy. Where do you come into this? He can tell you he loves you and he does want to be with you til he's blue in the face but deep down you know that's just words it's not actions.
He's a user and he will use you as long as you let him.
Don't do that anymore.
Your dc has you, my youngest is the same age so I can understand the questions and how much more sad it makes you.
The holiday... change it, take your friends and their dc with you. It's going to take big girl pants to do but you won't regret it.
Try the headspace app on your phone it's helped me no end when my mind was going crazy and I couldn't control my emotions.
It's not always as easy as LTB when your self esteem has been battered.
Start looking up. You can you this.
Fight then enjoy your holiday