Why not do both? Keep developing, but open source it so that others can help. I for one would be happy to help, since Sublime text is one of the few editors that gets most things right. Unlike vim and emacs it handles tabs and splits correctly. Unlike most editors other than vim and emacs you can make your own macros. The syntax highlighting isn’t limited to just keywords like some editors. It’s the closest thing to a decent text editor I’ve found so far (and believe me, I’ve tried at least 15 of them). Of my remaining issues (the fact that it isn’t free and the inability to resize the output panel) the first disappears automatically when open sourcing and the second I might be able to fix, particularly since, unlike most editors, this one isn’t written in a primitive language (C/C++). Also I would try and see if I can make an embedded interactive console, since command prompt boxes are annoying. Oh, and I’d try to make scrollbars appear only when needed.
Basically open sourcing saves you work, as people who want something can just make it themselves instead of having to open feature requests.