What do i do about mean girls at work?

i have been put in this situation at work where there are 2 girls that started and in the 3 months ive been there they have not only slandered me and several other employees but have gotten me pulled into the office to speak with the hr director 3 times in 2 months , in which at the meeting the hr lady directly said to all parties , in less there is physical harm being threatend on someone in the work place this is irrelevant(at this point i began makeing a log of harassment everytime something happened) . I appreciate that and can understand that workplace drama is un needed and can make for a hostile environmental . which it could have been droped . untill the next week when these girls scemed up a new plan to get me fired where they would claim threats on themselves from me ... to the extent of me bring a gun to work, making threats to them at work calling them out into the parking lot and slandering our hr department... IM TERRIFIED OF GUNS and im a non conflict person . At this point they are running a ongoing investigation... but if i lose my job .... im going to sue for slander and i was wondering if any of you could give me some tips