Drama at work advice

Andrena • Victoria's mommy 💓✨
So there's this girl who started a couple months ago, I've been here a year and it's hard for me to work with new people cause I often get frustrated after so much. Well this girl happens to be my boyfriends cousins friend and goes to a school I used to go to before I went to the alternative school I go to now. She took me getting frustrated with her personally, I wasn't a super bitch or anything but I'd have to tell her things way too many times. After a couple weeks she wasn't improving so my boss didn't give her hours for one week (btw we work in fast food and we recently hired new people after her who improved faster) he gave her one day the next week and I helped him with the schedule this week. I asked someone who was working with her if she improved and they said surpringly yes so I put more hours for her ( this was the first time I helped my boss make the schedule I usually just correct it afterwards when we're missing people). Anyways today I found out that she's saying she wants to fight me cause I'm the reason she hasn't been working and she doesn't care if I'm pregnant which I have no idea how she knows! Also she told a lot of people I'm pregnant at my old school which pisses me off because I didn't want people I'm not friends with or just random people knowing. Now I'm working with her Saturday morning and I don't know how to go about it I don't want to get crazy with her cause that's not appropriate at work but yet I'm super pissed I haven't had drama for over a year until now. Any advice on how to handle this would be greatly appreciated sorry for such a long back story 😅