My first post on MN so hope I get this right... 
I have a friend that I have known for two years. I have always considered her my best friend and while I genuinely love her, her kids can be a bit much at times. I have recently started getting closer with another mum of my sons friends and we do things together with and without kids. Now, my best friend always seems to be a bi disapproving as she seems to find the family a bit 'common' - at least from what i gather from comments that had been made.
To get down to it. This new friend has invited me and my kids out to the cinema tomorrow with her and her son. My best friend has just messages me asking what we are up to tomorrow afternoon as her husband has been ill and she wants him to have the house to himself for a while. I told her that this other friend has invited us out to the cinema and now she is asking if she can tag along. I really dont know what to say to her. My other friends and my kids really enjoy the cinema and enjoy watching movies. My best friend doesnt have that much control of her children and the last few times we have been to the cinema they have started walking around and chatting which usually ends up distracting my kids who then start doing that as well. The last time we went I dont think any of the kids got more than 20min of movie time and I had decided for myself not to go to the cinema with her again. That in combination with her not actually being too keen on this other person puts me in an uncomfortable situation and I really dont know what to say...
My apologies for the long story but any suggestions would be appreciated. We all have kids in the same class and my son is friends and I obvisouly dont want to offend anybody.