duvetdayplease, can I recommend that, instead of immediatelly cutting contact, you just withdraw. Cutting contact will just bring a whole heap of recriminations and blame onto your doorstep. Withdraw to the background, so they cannot say you are rude or ungrateful or too sensitive or any of the many things they like to throw at us scapegoats.
Just be polite but don't call or visit. Dont be available for them to come around. Don't encourage any contact, but don't prohibit it either - just manage it on your terms if you want to.
"yes, I know - we haven't seen you but we have been super busy...oh what a shame, we are not around this weekend, we are around friends Saturday and Sunday we promised the kids a bike ride. Maybe some other time? Next week? - no, sorry, we are doing XYZ, its been planned for ages. Im sure we will catch up soon...no, sorry, cant really commit to the following weekend at the moment as we are waiting for confirmation about a bit of a do. Why dont I give you a call when we know what we are doing." Deflect, deflect deflect. Polite but not engaged.
Dont get sucked into their little mess. You will be so much happier, and this way, its like a trial run for full seperation later.
You have your own family now - they must be your priority. Learn to leave all that hurt behind and resolve never to treat your own family like that.
I can tell you from experience of my own toxic family - where parents and 2 siblings and kids all went for a jolly to European country, and parents did not even tell me they were in the country - they live 6000 miles away, but could not travel 30 mins to my house. - I no longer have anything to do with them. Im still the family pariah, but hey, I no longer care. They tell outrageous stories about me and my DH, and I just think that the opinions of the people I do not know or care about are irrelevant. The people I care about (like my aunt) see through the crap.
SInce ridding myself of my baggage, my relationships with my DH and my DCs are better, I feel more in control and Ive changed the way I parent.