Are we gay? Should we experiment?

I have had a friend for three years, but we just became close last year. We are ALWAYS hanging out and we are best friends. It's a mutual loving "bromance" I guess. However, a few months ago we were having a sleepover as usual but this time, we masturbated together watching porn... ever since then things haven't been the same. We try not to talk about it and nobody else knows but us. The other day I suggested that the sexual tension between us was getting way too strong and we need to do something. The thing is we are both straight, I've had many girlfriends and my friend also talks to girls himself. We're not sure if we're gay, bi, just close, or if we should try and experiment. If anyone could help with some advice that would be great!! tHx :)