RNS...if the memorial starts at 7pm...get there at 6:55. That way everyone will be too busy to getting started to really love bomb you. That way you will also be seated in the back, near the door to make an easy escape. Your wife may encourage you to stay and talk afterward...or others may try and waylay you before you can escape. Use your children and the lateness of the hour to make an easy exit.
At the memorial, the only real faux pas you could make is eating some of the crackers or drink some of the wine...All you need to do is sit quietly and observe. And then get the hell out as fast as your can...unless of course you really want to meet some of the elders. If the purpose of going is to meet them, then the memorial is not really a good time...there will be so many people there that aren't normally there that they are going to be busy trying to meet and greet everyone. If it so you can get an eyeball on them so that you would recognize them, then just have your wife point them out to you. You should be able to tell who they are...the man giving the talk will definitely be an elder. Depending on the size of the congregation, the ones passing the plates and glasses most likely will be elders or ministerial servants.
Keep in mind, no matter how much she professes that she isn't going to try and convert you...she's not going to be able to help herself. Once you show up, don't be surprised if an elder, ministerial servant, or pioneer doesn't contact you and offer a study. She's going to be over the moon and most likely get a lot of attention in the congregation because you came. It may send her into full cult mode. She's already heading down that path since she has been put on reproof, just be aware it may happen. I know you are going to resist, and have no intention on going any farther with it, but they are not going to be convince of that easily.