I would leave them up. They are something you put effort and time into and that deserves to be displayed as a marked event in your life.

Plus, even though the pictures are associated with bad memories now, they were once a point of happiness. Rather than the bad memories, you can use them as a memory milestone of a happier time in your life.

You're welcome to be butthurt over the event. Nothing wrong with being upset. But don't let the actions of others take away from the creation of the art itself. ^_^
Maybe some day, after the pain of the event has passed, you can look back on the pictures more fondly. Until then, let the art and the memories rest comfortably in their place, pushed back to older pages by new art and new memories! :D

I suppose another thing I should point out is that my art quality has changed drastically. As such, I'm not really near as proud of them as I am with my current work. I feel like I wouldn't care as much if I pulled them off, and I honestly wonder if those involved in such pictures would either.

Bah. we all started somewhere. The scrawls we made as children are just as much of our journey as the masterpiece we will someday make.

Though its not my gallery so I cant say.

It's a love/hate relationship for me.

I know that feeling. I know it all too well. "Friends for freebies", until they get bored and leave. Ugh.

At least half of the time I see gallery nukes, people give the reasoning that they don't like looking at their old work. They hate it. They hate seeing what they used to do compared what they do now. Some kinda drivel.

Nearly the other half they give the reason you're giving. A lot of their art has bad memories attached to them, so they nuked their gallery for a fresh start.

Personally, I'm not a fan of gallery nukes, but I can totally understand getting away from bad memories. There shouldn't be anything wrong with wanting a clear mind and wanting to be happy.

It wouldn't be a gallery nuke, just a few images I'd remove. I somewhat feel like the people I did the art for do not really deserve to have it after how they've treated me, but that said, it's not like I can remove it from their computers if they decided to save it.

Ah. True, I have a few images like that. I worked for days, weeks even, on a single, free image for a friend to, well, be friendly. It gave them reason to ignore me more and more, so... I know where you're coming from.

Well, at the end of the day it is indeed your gallery. I say if it does give your bad memories that you'd rather not remember, go ahead and wipe them out. Although maybe give a heads up if a lot of other people like it.

I'd suggest removing them, as this is first and foremost your gallery and not anyone or everyone else's. I say only leave things here that you like to see. If they are linked to bad memories, getting rid of them is a good step in getting over it.

Even so, one of them is my most viewed and favorited picture... what if... I took the same premise and remade the old pictures with new characters, and used my more up-to-date style to really make them something new and fresh? Perhaps then I could remove the old, and my watchers would have otherwise the same content to view?

If that works for you at least. I think the more important point here is to separate yourself from the memories, since otherwise that may end up seeding a deep-seated discontent that'll be far more difficult to get rid of.

I would keep them.
Even though those 'friends' are gone, you still have artwork, and this artwork represents you and your art abilities, and neutral people and/or your watchers will enjoy the artworks too.