MAJOR Issues with My Fiancé’s Mom & Sister

Ra

I was lucky enough to meet the man of my dreams in the summer of 2017. This past weekend he proposed to me, with his 3 children involved, & thinking about how truly special it was still brings tears of joy to my eyes. My entire family has loved him & fully supported us from day 1. His family, however, has always treated me as though I have some ulterior motive in dating him, especially now that we’re engaged. His Mother has been totally supportive of me living with him for well over a year now but she’s always been quick & adamant about telling him she does not think he should ever get married again b.c of what he went through in his divorce (his wife, who he’d been dating since they were 13, had a very in-his-face & self-righteous affair, which would break anyone’s heart). I’ve never been anything but completely in love with him, totally supportive, & entirely accepting + loving towards his children. I just found out that his sister told him she believes I’m “not to be trusted” on Christmas Day & this is all b.c I suffer from migraines & was about 20 minutes late coming downstairs with everyone else. I’m beyond pissed but I don’t want this tension & contention between the 3 of us. I just can’t stand the way they’re both all smiles, hugs, & compliments to my face but the second I turn around they’re running their mouths & talking sh*t about me. This backhanded, two-faced gossip monger b.s. is already starting to draw a line in the sand & all I genuinely want is to clear the air & have everyone get along, & if not, then at least have the respect to talk to me directly rather than everyone else...Has anyone ever dealt with anything like this & if so how did you handle it (+ hopefully resolve it)??