among the three of you: yourself, your coworker and your boss.
1. You have no responsibility to report to your coworker or cover his ass, do NOT be a push over.
2. You have to say the truth and nothing but the truth to your boss in regards to the status of the project ( i don't care if your coworker is a good person or not, if he's not doing his job, then he's not a good team player) try to get as much in writing possible.
3. You need to hold your boss liable for the project, if he doesn't wanna talk to your coworker, escalade the issue to your boss' boss. Schedule a weekly project status meeting with your coworker and your boss and send a summary to all three of you after the meeting, copy higher directors if possible
4. Remain calm but always firm, under any circumstances, bad attitude and arguments will only hurt you instead of helping you.
5. Remember, smart people deal with issues, not avoid issues. Quitting won't help you a bit, you will have the same issue and same coworker elsewhere.
Good luck!
