Why does nobody like me??

Anäis • just a young Sagittarius woman enjoying this great big world.
So I overheard some girls I work with bad mouthing me in the workplace.  I've never bad mouthed either one of these girls (one is 21 and the other is in her late 30s) but for whatever reason they just completely threw me under the bus. I never get invited for lunches, I dot get invited to after-work functions, and I just don't fit in. I feel like the odd ball out. I'm also going through a very hard time right now personally so the fact l I'm not being appreciated in the work place is weighing heavier on me.
Is it me? I've always only been nice to these girls. Like very nice! What should I do? Kill them with kindness? Confront them? Or just write them off?