They are c*nts - and that's one of the few swearwords i rarely use because it is too horrible to even think.
Ignore them (easy to say, I know).
I was with a group of women on Wednesday and the conversation turned, as conversations do, to "What would you do/not do if you had your time over again.
Without exception, every single on of us agreed that we would take no notice of the comments or opinions of people we didn't know, didn't like, didn't care about us or we had no respect for.
You don't know this family, from what you have had to do with them you have no reason to like them, they don't care a toss about you, even to the degree of showing you any courtesy - and how can you possibly respect people like that? You can't. They have hit every button!
You have done amazingly well losing so much weight, and to have managed to go out of doors when you have been effectively trapped in your home for so long is beyond amazing.
I would bet you that none of them would have shown such courage.
Leave the note. It may make them less vile the next time (though probably not) but you will know that you have stood up for yourself, and will feel much better for it. Though personally I would also let down all of their tyres and pee in their petrol tank
YOU will get better and go from strength to strength. THEY will probably remain twats - as Judge Judy says - you can't fix stupid.