Is this wrong or ok?

So my best friend of 11 years dated this guy for nine days. This was about four months ago, she broke up with him & now whenever I mention him she calls him a loser & other names. We've always texted alot but lately it's gotten flirty and kind of dirty. We've been planning on meeting up & making out among other things (no ). Shea waaaay over him, hated him even. And he was never all that into her. He says all these sweet things to me & it's obvious he likes me. He also knows how to satisfy my.....other side with dirty talk. Why should I have to give up someone like this when my friends is over him. Do u consider it wrong??