How to deal with important but lazy collaborators? I'm part of a research project, initiated by another collaborator. The collaborator did the bare minimum of work to get the project started, but then completely stopped contributing, while I did about 90% of my part in the project. 

Now the collaborator wants to publish the work done, but without completing their part, by refocusing the paper and emphasizing my part as the main focus of the paper. The resulting paper is high on content (that I've written), but low on applicability/impact (due to the collaborator's negligence). It is also not worth the time I have put into it, since the collaborator's part was supposed to be crucial.

Despite their lack of input in this paper, the collaborator still insists on being the leading author (since they initiated the project), but the result is mostly my work. I may have to collaborate with them again in the future, so I do not want to alienate them by forcing my hand in this, but I feel like some kind of bait-and-switch has been done here. 

Is there a way to proceed without seeming unethical? I can't leave this entire project without wasting all my work. But if I don't leave, then the collaborator gets credit for the work I've done. 

Is there a way to stop this from happening again? Is this common in academic collaboration, and is there is a way to work with collaborators without this happening?
Honestly, this is a fairly common problem.  You see it  a lot at even the basic office group level where one person ends up doing a majority of the work.  If you've put in a lot of work and this is the only way forward then accept it and move on.  If you can't live with that outcome then pull your contribution and move on.  

In the future...well now you know what you look out for!

Either way, don't let this consume you.  There will be many more battles to fight in your academic career.