MIL made me feel unwelcome.

As you don’t quite get on with your SIL, what was the reason for staying? Drink?
How was you going to get back to your family given your wife has left? Taxi? Expecting wife’s family to drive you back?

I reckon you wanted to stay so you can carry on drinking. And you made your wife’s mom feel uncomfortable as perhaps they are not quite sure about you. You then made things worse by saying you ‘feel unwelcome’. MIL’s comment ‘i don’t know’ was your hint to say ‘actually, i will be heading off too now’ but you totally missed it and got confrontational because you had your eyes on something you wanted from that evening (drink?).

Im affraid, you came across badly. It was her family. She was leaving and so you should have, too.

You sound a pita, i wonder how the rest of the evening went after you stayed?

I jumped in and said ‘I’ll be leaving too. It’s clear I’m not welcome here’

That was an immature, unpleasant, and entirely unnecessary comment. Especially when made after a lovely wedding day. You really didn't help your relationship with your in-laws at all. You soured the whole day.

Since it's already been explained that the wife wanted to go back, and that she breastfeeds the child to sleep, there is plenty else to say apart from that.

If your wife was my sister I would think “doesn’t he want to go home and help her rather than drinking more?” plus “wow what a twat” when you were petulant about it

I’ve reread this and am really shocked you would a) let you wife go alone b) be so snippy with in-laws c) use the tone you have to describe this..

Agreed

To be honest, you sound neurotic and rude. Best to ask kindly if it’s ok to stay and if not go (there could be various reasons) rather than make a problem.

I agree with some that usually one would expect you would go back with your wife and child.

I suspect that your previous issues with SIL aren’t as resolved as you think they are. She might be trying to keep the peace for the sake of the family but still upset with you. What did you used to disagree about?

Whether or not you should have accompanied your wife and child back - and that’s between you - you shouldn’t have come up with the arsey comment at the end. You have just made things unnecessarily awkward.

Well done you for packing the car up so your wife could drive back for an hour alone to look after your child while you stayed behind and celebrated her sister’s wedding without her. You wife certainly lucked out there

I reckon your MIL was surprised that you weren’t going back with your wife, and in a way was being protective of her daughter’s needs. Especially when you had packed up the car, and the holiday cottage is an hour away. It does seem a little strange. Was your wife really okay with this? Being a mum I would imagine she would have welcomed a night off, or a bit of time for just the two of you, if you had spent all day with the in-laws anyway.

You are a dick, you should have gone with your wife, you clearly put yourself first and think everyone else should expect you to also. Have some respect for your family instead of trying to avoid being with them so you can drink.

The need for it is that they don’t like him / her

You should go home with your pregnant wife and toddler. Of course your in laws don’t want you hanging back just to get more drunk.

Yes your wife may be fine with it but her DM sees it differently and expected you to drive back with her.

no way would Ostay and party with my husbands family if he had to leave with our baby for some reason, especially with past conflict history. I getting fine with DHs family most of the time, but not way could i ever picture me doing this.

You made a mountain out of a mole hill and put the relationship back to not good.

What was the issue between you and SIL?
Wondering if it's made you extra sensitive.

Well you did take your life in your hands by asking here on Mumsnet, I hope you were prepared for the answers.
Personally I think YWNBU.

Your MIL and SIL sound like total gobshites. Check out immediately and have nothing more to do with the tossers.

This

If my dh was taking kids home mil would have absolutely made a comment saying I should be helping him. But i had been the one leaving she would have been encouraging dh to stay and have a break.

one thing though did you check they were happy to drive you back? It’s common courtesy to.

I agree - as it was your wife’s family & she is pregnant & breastfeeding and it’s an hours drive back, I’d have travelled back with her rather than stay out drinking with her family. I imagine my parents would have raised an eyebrow in those circumstances too.

You don't get a medal for getting your own baby up in the morning, doing breakfast and getting baby dressed. its your baby, your job. Wedding wise you should have gone home with your wife. Mother in law wise, quite rude tbh.

If you're being honest about pulling your weight and your wife not minding that you were staying behind, then I think they were rude.

There's a weird thing on MN where ILs are only to be spoken to through your spouse and any relationship outside your nuclear family is low priority.

If I had to leave my family party early and DH was having a good time, I'd want him to stay too. I guess the difference is, my family would want him to stay too as they adore him.

She’s pregnant why are you not doing everything?

the comments about packing up the car FOR her. My ex used to drive me insane by pointing out what he did (minimal) and expecting applause whilst I had difficult pregnancies and didn’t point it all out. He’s an ex.