jealous ex-wife making me MISERABLE!

My DH's ex-wife is ridiculous!! She was once my "friend" and we would do things together alone and with the kids. We went on a trip together and I made a huge effort by inviting her to my wedding and she made a fool of me. That was in April and things have not been the same since. I have my two stepkids Monday thru Friday which I ABSOLUTELY love! They are better over here in my opinion because I offer structure, stability, a loving enviornment and positive discipline (which I truly believe they crave.) At the beginning of the summer she emailed us with a list of Saturdays she could not have them. FINE! I don't have a problem with that at all--I wish we could have them 24/7. So yesterday was one of those days. We arranged for my SS to go with his friend to Six Flags and my SD to have a "girls night" with me. I was so excited and made a hair appt to get her hair fixed "fancy" and reservations at a cute restaurant where we could eat outside and then had tickets to the Muny for High School Musical. I saw the ex-wife on Friday and told her of all these plans. She acted all put out and said that the wedding she was attending started at 5. That means to me that Emma would be over here before that right? So yesterday, the woman did not call me all day to let me know when she would drop her off and finally returned my 5 phone calls at 4:30. She said she "didn't know I had all those plans" even though I had told her specifically the day before. I'm sure she was jealous because Emma was really excited for our night out. She ended up dropping her off at 7:00 without feeding her of course, so we had to get a quick bite at home. I wanted this to be special and Emma looked like she hadn't brushed her hair or teeth all day. AHHH! What does she want me to do? Not plan fun things for the kids to do so she can feel better? All this does is hurt the kids.....so sad. Then she told me she had planned a "surprise" to take the kids on a float trip today and she would pick Emma up at 7 am. So I set my alarm and Emma was up and dressed and fed by 7. She didn't show up here until 9:30!!! I TRIED to make things comfortable for the two of us but I guess that was a mistake too!!!!