Ok, here was the argument.
I was at the store, and she called me to ask about trading the kids for a day. I said no problem, if she wants to bring them over I would be home in 20, I'm at the store. She then asked if I would mind picking some stuff up the kids needed to bring for school (capri sun and snacks for 40 kids). I said no problem and picked the stuff up. So, just to set the stage, I had just agreed to watch the kids on a night I wasn't supposed to, and purchased some stuff that was her responsibility as well.
One more bit of stage setting. I've been to my ex's house a couple of times to get the kids or drop something off with my new GF, and my ex has stopped by my house when she was here as well. Now, I was a little bothered, because my ex has gone out of her way to pretend my GF didn't exist. Never makes any kind of eye contact, and never speaks to her, not that she has any reason too, but just weird and rude. The last time I had gone over to drop the kids off my ex said hello to me by name, then each of the kids by name, then started talking, just completely ignoring my GF, and it annoyed me. I understand she doesn't need to be best pals or anything, but she was just blatantly being rude, and I thought I would say something to her the next time it was just the two of us.
Cut to current times.
So, she arrives at my house to drop the kids off, and asks if my new girlfriend is all moved in (seeing the boxes and things). I told her basically yes, that my current GF was up in Phoenix for one more week, but that she was basically moved in. She kind of got a little upset looking and said "Ok, fine, bye kids" and walked out. I followed her outside and asked if we could talk for a second. I told her I knew she wasn't happy about my GF moving in, but could she please just try to act civilly towards her, and not ignore her.
Wrong move. She flipped the fuck out. THIS IS GOD DAMN RIDICULOUS! I believe is how she started it. She proceeded to rant about how if it were up to her she would stop me from letting a stranger move in, about how my track record with long term girlfriends over the last year is 0 for 3, and about how insulting and rude I'm being for not respecting her wishes and telling my GF to go get her own place. I'm staying calm and trying to calm her down, but its clearly been pent up and she just keeps at it, insulting me constantly and just kind of going off. She keeps saying how ridiculous it is for me to expect her to be best friends with this girl she doesn't know, and I keep saying I'm not asking for that, I just wanted her to not go out of her way to make my GF feel awkward or whatever. She keeps ranting, and then starts into "You know what, if she doesn't like it, how about she can just stay in the car when you come to my house, or better yet, how about she just doesn't come at all." and once she starts getting into the (sort of) threat mode I start getting annoyed, because she can be as unhappy with me as she likes and yell and scream if she needs to, but she doesn't get to push me around.
So I tell her "Before you threaten me anymore here, I want you to know that I don't want to go down that road. I like what we have right now, and I'd like to stay civil and friendly, but anything you want to lay out as a threat is coming right back on you, so if you want to lay down the "She can't come to my house or she needs to stay in the car" rule, than the same applies to you. If you need something you can stay outside and I'll bring it to you in your car, or I can go meet you at another location. Again, I don't want to go down that road, I like that you can come over whenever you want and come into the house and see the kids, but if you want to threaten me with that, just know that the same rules will apply here towards you."
And she backed way the fuck off, from 100% anger down to like 60%, she started back peddling into "Well, I wasn't threatening you, I was just saying...." and I said "Yeah, and I don't know why this had to be a huge fight, I didn't expect it. I thought I had a small request, and that was you acknowledge my girlfriend, you don't have to be her friend, or ask her day was, I just don't want her to be made to feel uncomfortable around you. I thought that was a simple thing, if you feel it isn't, and you can't do it, then that's the way it goes. If you can't do it, you can't do it. I just wanted to ask, because it makes me uncomfortable too."
She then said "Fine, I can say hi to her, but don't expect me to be her best friend." and I said "Thank you, I appreciate it." and then she said "You know what though, I want my name off this house... within 3 months. I might want to buy a place, and I can't while my name is on this." and I said "Fine, no problem." and she said "And you remember how much you nagged and nagged me to get my name off that credit card when we got divorced because you didn't know if it was getting paid and stuff, II don't know what you're doing with the house, so it's the same thing." And then I said "You mean the credit card card you never got your name off of? but yes, I know what you mean." And she went into "Well, I stopped using that card you know, I just haven't gone in and got my name off it....." and then the conversation just calmed down and she left.
And yes, despite the fact we have been divorced over a year now, her name is still on the house (all the divorce paperwork say it's mine though), because its going to cost me thousands to refinance it, and I was thinking I may sell it in the next couple of years anyway, so why bother. There is also still 1 credit card in both our names because we have to go to Chase together to get it cancelled, and she stood me up there 3 times before I just stopped stressing it anymore. Lastly, her car title is still solely in my name. I'm now in the process of fixing all 3 of these issue's.
Since the fight she has been nothing but roses and honey, she actually called me 30 or so minutes ago to ask me if I would be willing to go 50/50 on cost to sign the kids up for soccer and get all the stuff they need for it. There hasn't been a situation where my ex and my current GF have been together again, although this Saturday we will all be attending a wedding, so we'll see what happens then.
So that was the drama. No talk of child support or custody, just her being protective/whatever. My girlfriend is more amazing each and every day, and can do no wrong as far as I've seen. So, at least that aspect of everything couldn't be better. Well, and honestly, since the night of the fight, I've had no issue with the ex either, so yeah, life is going super well all around.