Metal and pop are like siblings, and all the, "One roolz, the other suckz!" is just sibling rivalry.
Is it wrong to feel shameful? I consider that the wrong question. You're questioning the validity of your own emotion. That's other people's job, and it's pointless enough when they do it. There is no true continuum of emotional validity; it's a fallacy of how we judge each other. You experience emotion, it is therefore legitimate.
You DO feel shameful. Should you? Of course not. Taste happens, you don't choose it. And there's nothing wrong with liking any music, no matter how bad it is in whose estimation.
But I put it on music fan culture, and how boring and unromantic it is, that you have to feel this way, not on you. Do what you're doing now, and face the feelings, as opposed to ignoring them, and you have the best chance of working through them, and eventually being able to enjoy the music you enjoy guilt free. Good luck.
Myself, I'm a big music freak, and my two favourite genres overall are probably metal and pop. I never enjoyed Slayer MORE than when I decided acting like an overly hormonal teenager isn't a requisite to enjoying it. And I enjoy Lady Gaga quite a lot without feeling the need to put my "paws up."
It's a tired analogy, but I'm not going to jump off a bridge just because people who like the same music as me do it.