I'm frustrated

So I had a daycare parent keep one child home sick on Tuesday (she has twins). They came back on Wednesday, Mom was then home sick Thursday and Friday but had Dad bring the twins to my house. Isabelle started throwing up yesterday. I know of one other daycare child that got sick last night when they got home too. This is about the 3rd time this parent has done this to us. She or one of her other kids was sick, brought them back to daycare too early, or brought them while she was home with someone else and it has spread something through here. It really got to me this weekend because our anniversary is on Monday and we had a date planned for today! Which we had to cancel - so cancelled our zoo plans last weekend and now our date night. This is a big deal to us, because we really don't do things by ourselves too often. Then I find out Jose had planned surprises for the date - I thought we were going to eat with my sister and her friend, but really that was just to throw me off. He had plans for just the two of us to go somewhere. It is so hard not to just call up that mom and give her a tongue thrashing, because she knew she would be exposing us and while she was home sleeping in bed, I was taking care of her children while they spread the germs! So I did write a letter to all the parents discussing the issue - which is about the 3rd time I've written about it, just because it's not only my kids their doing this too and this mom always says - I have to work, I can't miss work - well by her doing this it makes us all miss work and plans. It's just so selfish. I try to be patient and work with my parents, but this is at least the 3rd time I can remember, and she needs to know that it's not ok. One time she lied that they were fine, which really she had given them tylenol before they came to hope the fever would stay away long enough for her to work! So I'm ready to confront this mother and discuss my disappointment with her decisions - I always say that, but then I never really do. I did state in the letter that this issue is one that I would consider termination of daycare services - so I hope she realizes that I'm serious and she starts thinking of everyone else. I'm just so angry. Isabelle is doing much better today - threw up 3 times yesterday, slept a lot last night. She's eaten two full bottles - with pedialyte and watered down formula - and has kept them down. So we're on the mend. We're hoping that the other two don't start with it now - but we don't feel very confident at this time! Bradey's graduation party is tomorrow, so hopefully we can make it to that. I am just so tired of all the sickness. I hate feeling taken advantage of too as far as the daycare parents go. So another weekend the Sturgeons are quarantined in our house to avoid exposing others! It's just so frustrating.....