I wouldn't call it sexual assault (you voluntarily drunk the alcohol, you asked for a condom, you continued to hang with him etc.). You do own your share of responsibility in your actions and behaviours.

However, he took advantage and a true friend would never have tried to be intimate with you. His morals, or lack thereof, (i.e.cheating on their long-term partner, taking advantage of another 'friend') reflect the kind of friend, and man, he is. I would ditch him and avoid putting yourself in such situations in the future.