😡very angry😡

MY LITTLE RANT! AM I OVERREACTING! I am so angry with my sister:
It all started when her little one caught a cold (was still only a baby 4mths old) and I felt really bad because I know my kids had just gotten over there colds to, so I gave her some little hint and tips (this is her 1st baby) so rubbing baby vix on the bottom of the feet etc some advice that would help, 
She then turns and tells me : that I was my children's fault that baby is poorly and that I should keep a closer eye on my children so they don't get poorly at all (My children are hardly ever poorly they have a cold once a year if that ,kids all get coughs and kids pick all sorts up from school to) so I told her not to bring baby around before ringing or texting me 1st so I could let her know if my kiddies were poorly at all.... Well a couple of months went by and everything was good she would text or ring me to let me know if they were planning a visit. UNTILL she came around to my house (without warning,no text,call, nothing) the other day with baby all was good , my daughter sneezed once (wasn't in the same room as we were) and yet a few days after the baby is poorly again has coughs and sneezes and I know she is going to blame my kids yet again for it, (she pretty much has said it was there fault on another social site- her words were "just like last time baby was poorly" there is only so much I can take and I will not let her blame my children for every cough sneeze or cold that the baby gets, it is their house and I will not ask them to go upstairs etc when the baby comes around just incase baby gets the sniffles, I will not let her use my children as a excuse to why her child is poorly 😡😡😡 I know I will end up telling her not to come around anymore if she says anything to me !! 
I may sound like I'm over reacting but it really pushes my buttons when my babies are getting blamed for her child's illness ,,