If you're still looking to fix it yourself, iFixit's Nexus 4 teardown will probably help you in figuring out how to open it and take the broken glass back off. Honestly though I'd call that repair shop that someone posted.
I've also seen cell-phone repair kiosks in some of the larger local malls (e.g. the Burlington Mall (in Burlington, MA) nearby me has one) that are specifically set up to handle this sort of thing. I'm sure pricing and quality of work is quite variable, but if you do live near a larger mall you could wander around there and see if there is something similar in your area.