How can I rid myself of feelings of jealousy and envy towards my friend's academic success, even though I wish him well, and is there a way to strengthen myself to accept such behavior that displeases God?

You have done well in dealing with these thoughts before they escalated. What you feel is not forbidden envy unless it reaches the point of injustice or wishing for the removal of a blessing. You are permitted to refrain from participating with him in certain good deeds that might benefit him, as long as your participation is not obligatory. We advise you to make abundant supplications for your companion, for indeed, this removes what is in the heart, in accordance with His, the Almighty's, saying: "Our Lord, forgive us and our brethren who preceded us in faith and put not in our hearts any rancor toward those who have believed."