Sweetheart, this is as i suspected. marriage or getting PG are often triggers for controlling behaviour.
Presents/gifts etc are only gifts when they come without expectation or demands in return, or as a means for you stop being you and start doing what he expects in return.
YOU know that the gifts are not what you are in this relationship for, but HE is using gifts and trinkets to guilt you into thinking you are indebted to him somehow. it's CLASSIC controlling behaviour.
the sulking is starting, the not letting it drop, the verbal punishment, the guilting.
there is a script with this stuff, if you don't refuse to accept being controlled, it will increase, and escalate. in the end he could use silent treatment/stonewalling (ignoring your existence for weeks/months until he deems you having suffered enough) he will transform from guilting you and then work up to getting verbally abusive of you. over time he could graduate to physical.
What you do now will be crucial in the survival of your relationship. You need to state to him that you have agreed to go on the hen weekend, that you are going to honour it and that you will go on the groupon weekend another time. If he is going to sulk, admonish or make you suffer as a result, then he may as well write off the expense now, because you won't go.
Calmly inform him that you and he are equal partners in your marriage and that he has a right to make arrangements with his friends, as do you. It's not healthy or acceptable to demand or expect a partner to cancel their plans every time.
show what you will and will not accept. be firm and calm and you might just pull this around. Make sure he knows that this is non negotiable and you will walk if he carries on like this as it's not what a normal and healthy relationship is like.
My love, every single one of us here is 'on your side', your instincts have told you to post here, and they have served you well. Keep posting as you come to terms with what has been said here, i know it's come as an almighty shock.