So, I've decided to forbid my oldest daughter from spending the weekends with my Mom&Dad. The reason is simple: She refuses to stop feeding her an excessive amount of sugar. I always knew she gave her a good bit, but I never realized how much until my daughter came home this Sunday, and told us that she had 4 toaster strudels and 2 poptarts, for breakfast alone, on Sunday morning. She was sick Monday and couldn't go to school, and my daughter even said she thought it was because of how much sugar she had eaten. I went to talk to my mom about this, and asked her point blank to not feed her so much sugar(the breakfast thing is NOT an isolated incident, my mom buys Italian ices, 3 boxes at a time, and will give my daughter(Kiara) upwards of a box and a half in a single weekend, tons of chips, cookies, and other sugary treats). I pointed to the fact that I have diabetes and that I do not want Kiara to end up wth it as well, not to mention, being overweight my entire childhood/teenage years, I don't want her to be overweight as well. She refused to back down whatsoever, and when I said "Well, until you can reconsider, Kiara is no longer allowed to come over. Her response: So?. Now, I know she couldn't possibly have meant that, because I know how much she loves and adores Kiara, but the fact that she is completely unwilling to negotiate whatssoever royally pisses me off. I even told her that I don't mind her giving her SOME sugary things, especially since we really don't allow that stuff over here, so an indulgence once and a while over there is ok, but not to the extent that she currently allows.
So, am I wrong here for caring about my daughters health? I broke the news to my daughter and she has barely stopped crying in an hour, It's broken her heart, but I just don't feel I can back down in this situation. I often fight with my mom over how to raise my daughters, but none of the other fights are nearly as serious and potentially life-threatening as this one. Opinions?