Need advice

So my best friend has recently gone behind my back and repeated/twisted something I said to someone. I own up to the fact I shouldn’t have vented to her, but I’ve never repeated anything she’s said about the situations. I trusted her during this time as I am slipping into depression. I’m so tired of being the person that walks away from it quietly. I think she needs to know what she did is not ok and I know about it. I’m not good with words though. I’m trying to put this in a way she can’t say I was rude or out of line (she may try but I want to make sure it’s not). Any suggestions?