Would i be a terrible person if i dated my ex's best friend?

[Tayluhsalad]

ok. that question sounds terrible but its so complicated. Me and this guy dated off and on for a year. he was the worst bf ever. He made fat jokes, wouldn't go out in public with me, said i was ugly. well finally once when we were not dating he invited me to a midnight game release that he and his best friend were going to. i had skyped with the two plenty of times but i wanted to meet his friend so i went. well after his friend started messaging me on facebook frequently and one day he came and hung out with me and one of my friends. well he held my hand, and four movies later he kissed me, and i really like him. and i feel bad because my ex is spamming me trying to get me back...like made a 12 min long video on youtube professing his love and shit. so...is it wrong to date his friend after he was so shitty to me?