I don't know how far along the character copies are from the main game (having to re do some of the characters so they look the same, similar as the main game), but surely you should be working on chapter 4 and trying to get it released as soon as possible. Working now on 3 games is a wee bit daft when your main game has not had an update in such a long time (couple of years), not withstanding all the issues you have faced over that time.
As others have said you need to focus on the main game, you can always work on the prequel and of course MNF 2 after you have released chapter 4. People have been waiting for this chapter for a very long time. I think you owe it to them with all the support they have given you. I think not doing so, is like a slap in the face to them. They won't necessarily say it but someone has to, and I hate that I am the one, but surely you know this correct.