Troubled Waters

As I have previously mentioned, the Ex and I get along fairly well. As far as ex's go, she is decent in my book. Buuut, good things never last do they? Last weekend we had to drop the chillins off early because we had a friends baby shower to attend. This is the SECOND time in all the times we have ever had them that we had to drop them off earlier than four. She starts laying in on us about how "that's her only time alone and are we going to be able to keep them longer next weekend because she can't keep doing this" and then she continues with "oh I see you took the kids shopping and bought them clothes well, 7K doesn't have any jeans did you get her those? No?! What? Why not!! blah-de-freakin-blah"
... I'm confused. Did I miss something? Where was the psycho memo? All of this in front of the kids too. So I'm standing in her kitchen, in between her and my future husband, and they are screaming at each other. Talk about uncomfortable! Then, to make things more fun, Monday I went shopping to buy 7K jeans because apparently we're psychic and knew she didn't have jeans but just wanted to stilt the child, and so I call the Ex for her size. I'm pretty sure she's a 6 because she's really skinny. That conversation is quick, to the point, and done. I don't enjoy calling her and feel really awkward doing so when C is not around. So I go to pick C up from his class and she calls right when he gets in the car. She then proceeds to tell me that she 'wants to talk to me when C is not around because I ''understand'' and she told him she wants new years eve and did he talk to me about it?' 'uh, no he hasn't actually because we are already making plans to go to Vegas for new years because January is a big month for us. It is both our birthdays and also the month we announce our engagement' She then launches into a tirade about how she NEEVER gets New Years eve (except last year) and how dare he plan anything when he promised her he would have the kids?!
At this point I've lost the capacity for speech. C is mouthing to get off the F-ing phone with her this instant, but she won't shut up! Then she tells me that she wants us to have the kids during the week to spend the night at least 1 night. Ummm, last I checked they go to school about 40 minutes away from us with no traffic! That would mean sitting in traffic for over 2 hours to get them to school then try to make it back to work? no. I don't think so. At this point C is making hand gestures and is about to tear the phone from my ear so I tell her I really have to go and lo and behold, she continues her rant! I'm holding the phone in my lap telling C that she WON'T shut up and I can't just hang up on her! So finally I get off the phone with her, and C immediately calls her from his phone and starts yelling that 'she can't do that, just because I'm nice and I listen to her, those are his kids and he's the one she needs to talk to and not get me involved' And when that man yells...the world shakes and babies cry. So needless to say I almost start crying.

Someone tell me WTF happened here? Why in God's name did she call me? I understand he yells, and it's scary, but damnit woman you've been putting up with it for almost 10 years! Not my place! Why is she rocking the boat? *sigh* I don't get it.