I fortunatly havn't been through that situation, although I had a little similarity with my girlfriend still having trouble with ex's.

I suppose it's hard to draw any comparison's between mine and your situation, but I can offer my opinion based on my experience... Their was one guy that kept calling my girlfriend up when I had just started seeing her. He was a right asshole as well, and just the thought of someone like that truely does make your blood boil.... Don't feel bad about that part though, it's completely human.... Our evolution has built up a million ' angry ' chemicals, that pump through every inch of our body at the very thought of another man messing with the livelyhood of the one we've chosen to protect (your Mrs Memphis). Those chemicals definetly helped us a few thousand years ago,,,,, when a challenge between 2 men over a woman probably meant a dual to the death,, literally.. So the feelings are naturally pretty freakin intense!! Sometimes they even feel like life or death... Their were times when my girlfriend would tell me stories of what her ex used to be like and how he treated her, and i'd literally stand up to look for my keys, to drive to his house, to baseball bat him until he died... But i'm positive that wouldn't have helped... In this day and age anyway .. In my younger days I would take my ego and run with it, and ended up getting into a few scuffles with guys i'd known for a matter of 1 second, but that i'd heard had messed with my girlfriend.... All it's taught me though is keeping a level head and staying logical is the only way to go... Which obviously you are doing by posting on here... Then you can try to semi-detach yourself from the situation and really think about what's going to be best.. Best for the kids, best for the future, best for the time he's around, best for Mrs Memphis, best for you, best for everyone, including that turd eater that's insisting on making your life hard....
Even taking out a bit of paper and just writing down your thoughts and plus' and minus' of different actions you can take is going to let you look at it a bit more methodically and keep emotions out of it at least a little... I know it would be next to impossible not to have emotions about it,,,, but looking at it as logically as possible now,,, could hopefully prevent having to go through a TONNE of shitty emotions later on, when no one has any control over what's happening.....

That's my only real suggestion, as unhelpful as it may be.

Although I don't know to much about the specifics, I can understand why your Mrs may still be a little intimidated by her ex... It may not be in the same way she was intimidated by him in the past,,,, but as he is coming around to visit the young ones, i'm sure she's aware just as much as you, that he is in a position now where he can really cause a bunch of people a LOT of heartache and a lot of crappy feelings if he decided to be a total a$$. That would be an intimidating feeling for the mother of a few children... So you can understand why the little things she DOES have control of in this situation, she wants to keep them as neutral as possible so as not to make the situation worse, or put it in a position where she doesn't have as much control.... But i'll leave it up to you what you think will be best with this situation... I don't think it would hurt that much though if it's just left to him to work out the situation between you and the mrs,,,, but yeah, you guys are in the best position to assess that.

My final suggestion, and this is something I have learnt time and time again with people, is that moods and tensions have a huge ability to project out from one person and spread to everyone else without any trouble at all....... Like e.g. If a guy wants to pick up a chick and walks up and talks to her nervously, she will feel nervous along with him. His nervousness will project onto everyone around him. If a confident guy came up and has the confidence for the both of them, she will feel comfortable with him......
What i'm getting at is, when the time comes when you actually have to sit in the same room as this guy, you may have a million intense emotions going on, but if you let them get the better of you, and you starting getting angry and uncomfortable and start to feel out of control, they'll quickly transfer onto everyone in the room without you saying or doing a thing,,, and the situation really will start to turn crap...... If you can really work hard to staying relaxed and comfortable and confident,,, and just project for yourself that you are relaxed and in control and taking it all in your stride, you could do a LOT worse than projecting that sort of comfort on to everyone else..... This may be one of the most important things you can do for EVERYONE, and technically YOU can control the entire situation just by staying this confident relaxed person..... When the guy had a scuffle with the last person your mrs was seeing, it may have been because tension just sparked off the instant they met, because,, wellll, they probably both were worked up and it was just inevitable that shit was going to start between them....

People on here know you're a sort of person that doesn't take shit... And you should know that you don't need to prove anything to anyone... So just relax, and you'll OWN the situation...
(darn I feel like freaking Anthony Robbins.... Someone slap me)


Anyway, i've rambled on long enough.. Hope all that is readable... I'll post back again if you want any more feedback or help...
It's a crappy situation, but respect for sticking by your girl and being mature enough to want to do the best thing for everyone... Lesser people would be planning a way to kick his ass before he's turned his car off in the driveway... Which would help no one...
CC for good luck!