My SIL plays too rough with my baby. Am I being too sensitve?

My SIL plays rough with my 10 month old. I feel like it is pive agressive, and I don't know exactly how to deal with this, other than not leave my baby unsupervised with her. Most of her games, seem innocent. She plays peek a boo, but then will suddenly yell "arrrhhh!" and frightens my baby, who cries. When my 10 month old cries, my SIL will call her a "titty baby" and say she needs to "toughen up". Or she will give her a sip of water, but allow the baby to get too much water and start choking. I picked up my daughter and removed her from SIL- when SIL was over last night, but I am upset about this- and I want to find a more permanent resolution. SIL seems to love her niece- but I don't want my confrontation to cause her to do anything more sinister or mean to my daughter to get back at me. How should I handle this? Oh, SIL doesn't have kids and really wants a baby, but had a hysterectomy, back when she said she didn't want a baby a year ago.