Don't know what to do

[Unicornsanddinosaurs]

So I got engaged at Xmas but despite hoping for ages that he would propose now that he has I'm not sure it's what I really want.
Will try to keep it short. We have been together nearly 6 years, both have a child from previous relationships and we have 4 month old together. We have had to deal with lots of hassle form both ex's, my ex now rarely sees my dd. Despite having a court order in place and working well for 2 years we are now back in court regarding contact with his dd.
I do love him but I just don't know if I can deal with constant trouble form his exw. We deliberately waited til things were sorted with his dd before we began ttc but as soon as his ex found out I was pregnant she started making contact difficult till eventually we had no choice but to take it back to court and we have said this will always be the case, everytime we think we are moving on his ex will cause problems.
On top of that the whole engagement thing has been a bit of a let down, he proposed on Xmas eve so it all got forgotten about in the midst of Xmas, the ring didn't fit, couldn't get it resized and they don't do it in my size, and it has been hard to get another one so still don't actually have a ring, he didn't tell his family and they found out via a congratulations message on Facebook so were a bit upset and then I discovered that he had also proposed to his ex on Xmas day 10 years ago which makes me feel, I don't know, weird or something, I'm not sure exactly it just ruined it a bit for me somehow.
Now we have just spent the last 2 and a half hours arguing/not talking cause he's pissed off that we didn't actually kiss and shake hands at the bells despite the fact me and the kids all stood up and knocked glasses said happy new year then my dd ran outside to see the fireworks, all the while he stayed sitting down and didn't stand up till I had left the room to follow my dd outside, apparently I should have waited and kissed him. I see it as a bit of a miss communication or whatever and not really that big a deal but he said iv ruined new year.
I was already a bit upset re the proposal but had decided it didn't really matter that much in the grand scheme of things and wasn't going to mention it but now I have in the argument tonight and his response was that he's just ignoring that cause now I'm trying to make it all about me.
I honestly don't know what to do, neither of us could afford to separate at the minute and I don't know if that's even what I really want, I don't want to upset all 3 of the kids by splitting up and we do love each other, get on well most of the time and could be happy but it's just so hard with everything going on in the background with his ex and arguing over stupid things, I don't want to end up getting married to then get divorced.

Sorry that was much longer than I anticipated, not even sure what I want people to say think I just had to get it all out.

I don't know what to say to you Unicornsanddinosaurs but feel some of your pain. I find it hard to feel sympathy for your partner.

Time to re-evaluate.

Wish I could say congrats but that’s one of the most unromantic stories I’ve ever heard. I think you would be both better separated

Sit back, get your child court orders sorted.
Get your ring sorted.
Worry about everything else later.
Take time to think about what you want.

There's a lot of expectation on having the perfect Christmas, perfect New Year, perfect engagement. I think emotions are high and rolling, especially with a baby and possibly lack of sleep.
The court order for his child is a stress, but it's separate issue from your relationship. It's understandable that the trouble with his exW affects you.
The proposal, well, I understand the disappointment at knowing he had done similar in the past. However, it might be the case that he wanted you to have what he considered a good proposal (in his mind and those who advised him). It doesn't mean you are supplying for the ex, but that he's moved on so much that he's happy to do something similar because "this time it will be better" and "My ex doesn't own the day and the proposal, I'm not allowing her memory to taint it, OP deserves to have this because I think it's the best time to propose". I think in his mind Christmas time is a special time and wanted to do it then. He chose Christmas Eve this time, so he didn't chose the exact day, might have intended to give you more time before Christmas day takes over the excitement but backfired?
You can get engaged and plan to get married in 3-5 years, so you can work out for longer if this is what you want, the issues with the children might sort themselves as the children grow and are able to express preferences, maybe hit teenage years and have more personal choice, other x-partners find something better to do than making life difficult, etc.
Being that your post doesn't bring problems between you other than miscommunication and over-reactions, and the big problems seem to be about exes and children, I would get engaged and plan to marry in a couple of years at least, see how everything pans out, save for the wedding (get wedding insurance), etc. You say you've been together for 6 years, but I think a baby always brings a new layer of tiredness and tensions to any relationship. It might be just that and everything chipping at it on top.
I don't know, it doesn't read as problems between you two, but as being overwhelmed by a series of annoying but minor events. I think he was childish to complain about the kiss, but I also think it's childish to complain about not having a ring (you did, you had to exchange). If anything, it's a silver lining: you get to choose what you want and you will be able to restart all conversations about your engagement when you finally get it and you get to show it around. As it will be probably after the Christmas holiday period, the conversation won't be overshadowed by it?
Hope you are feeling better today