Lukaku, 19, accused Villas-Boas of ostracising him from the day he arrived at the club.
Belgium striker Lukaku was signed for £18million at the start of Villas-Boas' doomed reign as part of a long-standing scouting project but the Portuguese hardly gave the youngster a look-in.
Lukaku told Sport Wereld: "There is one person that I will never forgive for what he did to me - the previous coach.
"It's not just that. It was also the way he spoke to me and treated me.
"Right from the beginning, it was weird. I could not stand how he was treating me. I received no explanation.
"In training, he put me on the right or left wing. In training matches, I was a substitute with a shirt to keep swapping teams. I really learned nothing!
"I have told the club that too. I understand that he was under pressure, but I was also thinking of myself. I have improved in recent months."
Lukaku only had a little more game time under caretaker manager Roberto Di Matteo and was not in the squad for Saturday's Champions League triumph.
He was nevertheless delighted with the outcome, saying: "I could not believe it. I had to think, 'Is this really happening'? European champion... My life has changed and I'm only 19."