Sex with a friend?

Okay so I recently got out of a relationship of a year and a half about 3 weeks ago. Im happier than ive ever been. Happier without him. He was my first love and first everything. But now that im back to normal i am so horny. Like ridiculously. The opportunity might arise to have sex with an old friend in a month or so and I really want to. But I always had this idea that the first person i slept with would be my only. But obviously he dumped me so thats not happening. I dont feel like im worth any less bc im not a virgin. Ive always been inbetween fucking literally everyone and just fucking as little as possible. Idk its a fantasy of mine to have random sex with a guy. And i know this guy. But im afraid id regret it? I have no clue but im horny. Help? I know i should only do it if im sure but i know itd probably be really really good sex. (Im 18 btw).