My question is can I sue him for bailing out and paying his rent plus late fees regardless of him filing bankruptcy?

The automatic stay is immediately effective upon the filing of a bankruptcy petition. Thus, before you could file suit, you would have to file a motion for relief from the automatic stay. The court cost to file the motion is $176.00 and it is unlikely that the court would grant your motion based upon the limited facts that you have provided. If you choose to file suit in state court without relief from the stay, then you will probably be responding to a motion to cite you for contempt for violation of the stay during the case or as a defendant in an adversary proceeding (a lawsuit filed within a bankruptcy case). If you wait until the case is over, then the discharge order discharges almost all debt, including back rent. Filing suit to collect a discharge debt can also result in a judgment against you for fees and costs.

When someone actually files bankruptcy, all legal action must be funnelled through the bankruptcy cort. Ignoring this requirement can come with a high price. Don't know what paper he gave you, but if it was a form 309, it is a bankruptcy notice. Check the date on this notice. Any debt made after the notice date would usually not be covered by the bankruptcy. Hope this perspective helps.

The bankruptcy filing stops you from successfully suing him. Your best bet is to find another roommate.