You went without a spotter and you can’t finish that last rep. Trainer Bill Hartman, has your exit plan

If you insist on going solo at the bench, remove the collars from the bar. The risk of having to rerack the bar if the weights slip is eclipsed by the potential benefit of saving your rib cage when your muscles give out.

If you do find yourself failing, use your remaining strength to carefully lower the bar to your chest – but don’t let it rest there or else you may injure your ribs. Keep as much upward pressure going as you can so you aren’t crushed.

Inch your dominant hand toward the end of the barbell 
so that the weight gradually slides off the opposite end.

As the one side of the bar dumps the weight, the unevenly weighted bar will quickly make the weights on the other side dump off as well. Keep a firm grasp on the bar so it doesn’t rocket skyward.

Push the empty bar to the rack and breath a sigh of relief.

Next time you approach the bench, ask for a spotter!