Make sure it's loading in large assembly mode. It should be doing that automatically, but if it's not, that will help a lot.
Also, you can load sub-assemblies in lightweight mode. That reduces the load on your computer.
Look into de-featuring parts. For example, most of the time you don't need to show the threads on a bolt. You just need to know where the bolt is.
You can open a smaller document and make sure those settings are the way you need them to be, and then try opening your large file.
Once you've reduced the assembly as much as you can, re-save the part and see if that has reduced the size enough to stop crashing your machine.
Hope that helps!