How do I turn down an invitation to a kids party without sounding rude

Backstory: when my daughter was 3-4 she was in preschool at a day care while I was at work. This one mom would start conversation with me if we both happened to be picking up our daughters at the same time. I would be polite but I never had interest in being friends. She's in her high 30's and I'm 24 so I didn't think we.d have much in common either. One day during a week the day care teachers were teaching our kids to memorize their home addresses I came in to her having my daughter tell her our home address and she was writing it down. Eventually she cornered me and we exchanged numbers (again I did this to be polite because she put me on the spot in front of ppl asking for my number) Our kids are now in kindergarten and go to different schools so I haven't seen her or her child since August. She's texted me twice saying her daughter misses mine and we should set up a play date. I'd respond like yeah sure let me know. I didn't want to be rude but again I have no interest. Our daughters were never best friends they played together but my daughter never really spoke about her how she talks about the kids she plays with most. The mom texted me last week asking for my address to invite my daughter to her daughters party. I didn't respond. The next day she texted me again asking and I felt bad so I told her. I got the invitation. It's for like 10:30am on a Saturday or Sunday and I really absolutely don't want to go at all. I hope this doesn't make me a horrible person. How can I tell her we can't come without sounding really rude. I don't mean to be a bitch or mean but I never tried to contact her or set up play dates and I'm sure she's probably really nice but I have no interest and honestly her kid was rude/misbehaved when they were in preschool. I really have no idea why she still contacts me or wants our kids to play together so bad. TL;dr how do I turn down an invitation to a kids party without being rude? In reality I have no intentions of ever setting up plans with this women ever. via /r/Parenting http://ift.tt/2nvu5J2