my thoughts

You deserve a talk to his boss, my thoughts, though.

Do not get personal.Statement like "The truth is that he ....is only involved in what he likes which is not much related to our business." is not helping you regardless. You'd better let his boss to draw conclusions on your supervisor's integrity with your achievements and contribution to the team during the course. You are not in a position to make accusations to your boss. Instead, you have to manage to do your best to lay out all the facts that counter his accusation in a professional way. A starting point, as you are talking to his boss, would be that you agree with your boss that your team may need addtional resources. However, it was not due to your performance....blah blah.. 

Further, your supervisor's integrity may have been well known by the whole Dept.