First off they are not entitled to your medical appointment information so tell them that, it's private.
Above everything else you really need to simplify the issues at hand and focus on your priorities.
You have gone through hell for this baby, I view IVF as hell having witnessed how tough the process it is.
These people and their demands and drama really needs to be put in its place.
They are not important IMO in the scale of things and all you both have been through.
People who behave the way they do bring nothing to the lives around them.
They sour and poison the lives of those whose lives they inhabit.
They ruin happy times and they bring stress and upset through their huge entitlement to attention, when none was necessary.
I am heading for 60, and like lots of posters telling you to brook no bullshit from these people, we realise that people who create drama add NOTHING to the lives of those around them.
Their entire focus is themselves and their ridiculous needs being met.
You have this beyond precious baby coming soon and yet you are thinking of how to manage these people.
Really sit with that.
All you have been through.
The stress, the process, the fingers crossed.
You have been so blessed with this pregnancy and yet these people are causing drama.
So awful.
Back away.
Don't go near any party.
Do not give them the approval that going will indicate.
@SpinningTheSeedsOfLove correctly suggested that you tell them that you need space after the mothers day drama.
I wouldn't get into any conversation.
I would text that your priority is your pregnancy and staying well. Their behaviour over Mother's day was just TOO awful, TOO upsetting, and wholly unacceptable.
You want space from them and their drama, as your priority is a calm restful environment for the duration of your pregnancy.
As a result you will be taking space.
You owe them nothing.
Your loyalty is to your precious baby, yourself, your partner, your new family.
The happiest, wisest posters are those that are firm on boundaries.
These people couldn't possibly genuinely care about you or your family, creating such completely unnecessary drama whilst you are finally pregnant.
I cannot stress enough how much you will bitterly regret allowing them to have an influence over this precious time, which is so fleeting, and passes in a flash.