Angry

I'm not sure what to do anymore. I have this friend that is taking way to much advantage of me. I thought her husband would have kept thier child so I could teach my class today and of course he didn't. So I had to stop teaching my class to take thier son where he needed to go. Don't get me wrong I love the kid but with him being diabetic it's hard for me to be able to walk the way I want to in the afternoon. Because most of the time it's 6-8 pm before she picks him up. It is very frustrating so it's taking a toll on my weigh loss because I'm so aggravated I want to eat to surpress those feelings. God is doing so much in my life right now and I feel as though this is a thing that needs to be removed. It's a huge burden on the things I want to do like walk or run. If I say something to her it just goes in one ear and out the other cause it just keeps on. I had to lose the friendship but it had to go. It's like a thorn in my side. I have her child from 7 am to 6 or 8 pm. It's really a hinderence. I just God to take it way. It had cause my head aches to come back and I have stepped out of the joy of the Lord because of it. What else can I do? It is really hard my husband and dad have told me to just tell her bye but in my heart I feel as though she still needs me. I haven't been able to exercise in 2 weeks because of it yes I have has weight loss in those 2 weeks but I feel like it could have been more if I would have exercised. I'm just at a lost. I feel as though it's a block to the doorway God wants to open for me. What else are my choices?