So a little background on said bridesmaid:
She introduced FI and I and as soon as we were engaged, I really wanted her to be a bridesmaid and asked her to be one. Yay! All glittery and butterfly farts!
She is 20 and has two kids. At the time, the guy she was dating (not the father of either children) was a totally cool guy. He was so helpful with the kids and I was really excited because he could wrangle her two children during the ceremony and at the reception, when she would have to sit up at the head table with us.
Now, she is pregnant with the third, with said guy, and he bailed. I was shocked and hurt for her, but this is life.
Now I'm really hesitant to have her as a bridesmaid, or even at the wedding in general, because her kids are exceptionally rowdy and ill-behaved and even more so now because she will not have someone to tend to them.
It's also a crazy coincidence that she is due close to the wedding, which means she will be uncomfortable and tired of being pregnant, and it'll make her less mobile to watch her kids.
I have every intention to make this whole wedding as kid-friendly as I can, even with a "kids corner" and hired help, but I cannot depend on our hired help to keep every child contained at all times.
How can I politely tell her I changed my mind?
I'd rather not entirely end our friendship, but since I don't support some of her behaviors anyways, I would not be heartbroken to never speak to her again.