A novel never ending.
Question: I am currently writing a novel called Elias (name of the main character). The whole story is intended to to introduce a series of novels and short stories from another character in the story, but I don't get to the introduction of the character I want to introduce and every time I write something of that specific character, it feels wrong so I keep writing the novel. Now this novel stand in a massive 200,000 words manuscript and expanding. How do I stop myself from writing and finally introduce the character for the next novel?
As John Lennon said, "Life is what happens when you're busy making other plans."
Do the work that's in front of you now, and worry about the other sstories later.
Right now, you have a story that is taking shape. Let it happen. Make this story the best you can. If you never get around to introducing your other character, so what? You can always introduce that character in a different story, where it feels right. (If it feels wrong to put the character in this novel, trust that feeling.) One of the great things about writing is that sometimes what you write turns out better than what you planned to write.
If this novel turns out great and gets published without your other character making an appearance, will you really care? Will any reader care?
You may find (when you get to the next novel) that it is better to simply tell a story about your other character, with no introduction. Introductions are often not nearly as interesting as the main event and can be skipped.
Incidentally, 200,000 words is about twice as long as a first novel should be. You may need to tighten it considerably in the revision process. Fortunately, it's always easier to cut than to pad. But don't worry about that now either. Just focus on creating a satisfying ending.