Hi Vanessa,
This may be hard to believe but your sister being cruel is an indicator of GUILT. Yes, guilt. She knows very well that you took care of her son, that she owes you money, that she’s a slob and that the boyfriend doesn’t look good on paper. It eats at her that you gave her a huge blessing of insisting that she move into your home. And that she blew it. And that you had to kick her out.
Your sister is feeling shame. She is feeling guilt. Her only defense? Act meanly to put you in your place so you two are on an equal footing at last!
My suggestion is that you take a break from family gatherings for a year. Next year arrive late, leave early, and be surface-y polite with your sister. Hopefully by year two or three she will have another boyfriend or the bad habit of bad mouthing you in your hearing will be broken.
As for holidays, have them at YOUR house. The sister won’t show up, and if she does, she is more likely to hold her tongue as ONCE AGAIN, she is on your turf, and will be reminded of the situation SHE put herself in. If she says something she will look really bad as you’re the host.
Best,
Inky
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