Moms husband has herpes!!!!

Im posting anonymously for a few reasons but my kids are 5 months now and my mom would like us to come visit for the first time for Thanksgiving that would be completely fine buttt her husband has herpes I know this bc she told me venting about him cheating and contracting the disease I really don't care for this piece of shit husband of hers has cheated multiple times w people younger than I am!!! im only 21 u guys.... he has been told multiple times he's never allowed around my kids for sooooo many reasons my mother will not leave him and I feel bad for her because she has yet to meet her first grandchildren. Am I over reacting by saying no and keeping my kids from her since she won't leave this disgusting man and won't even leave him alone to come to visit bc shes scared he's going to cheat. I live 3 hours away btw. But I find it unreal she won't come visit her first grandchildren bc of a man.... I know he's going to be there Thanksgiving and I will not take any chances a i wrong ?