There is no easy way to separate the digitizer and the display without damaging either of them. I'd recommend getting both the screen and digitizer for a much easier repair.
Since the Nexus 5X is a phone it will be hard to get the assemby (screen and digitizer assembly) on eBay or Amazon. As of writing this post there are probably a lot more random people having these assemblies. I recommend looking up the model number of the Nexus you have and searching "replacement lcd digitizer screen assembly for Nexus 5X" on eBay or Amazon or whatever you use and going from there. If I find anything reliable I'll link it on this post or another comment.
If don't want to do the work and have the money just give it to someone else to fix.
-Jono