Don't know who to believe. sorry so long

so yesterday my sister in law informs me that my mother in law and grandmother in law have been talking shit on me behind my back. I had my sister in law repeat it in front of my husband when he got home well he said he would say something to his mother which he did but after the fact she denied saying anything like always and says that the sister in law is just trying to start shit. this isn't the first time or the only person I've heard things from so now I don't know who to believe either way I'm feeling extremely uncomfortable in my living situation and my husband of course is believing his mom and saying that he thinks his siter is just trying to start drama. she's never lied to me about shit before why would she now? just really pissed off and uncomfortable because it's always a bitch about something I do or don't do.ugh!