Ex's best friend

So... I used to date this girl Stacy and we went out for around 2 months and I broke up with her. We are very close friends now and I got included in the friend group (Stacy, Haley, RJ and Ryan).

I've known Ryan for about 5-6 months now but it feels like I've known him forever. . I knew when I first met him that he was attractive to me (but I wasn't gonna say anything since I was dating Amy). Ryan and I are starting to talk by ourselves more and plan to hang out alone more... I keep having fantasies and dreams about him (not just sexual, some romantic too).

But... he's my ex's BFF... and Haley's Golden Rule is "No Dating in the Friend Group" but... that was the rule when the friend group was like 12 people... now it's just us 5.

I'm not sure what to do... I think if I really really want this to work I have to be quiet about it for a year or so and just try to be closer friends to Ryan but I'm scared I'll miss my chance... Help!