I have a serious problem with porn

I don't know if this is the right place to put it, but I didn't think anywhere else was right for this.

Anyway, for quite a while, i've looked at porn and hentai and fapped to it day after day. Although, all that time I felt like it was wrong. But I had no reason to stop, and I was lonely as shit so there wasn't really much supporting my need to stop.
But recently I got a really nice girlfriend, and I feel like it would be the right thing to do to just stop. But the thing is, I can't, and I feel like a complete dick because of it. I've managed to stop looking at regular porn and just fapped to ecchi, but even then I slip up sometimes. I've tried over and over and over but I just can't stop. I don't want to screw it up between me and my girlfriend. And I feel like i'm being really unfaithful. So, if anybody could please help me with this problem, it would be greatly appreciated.

And don't post shit like "kill yourself" or "chop your dick off". I'm asking for help and this is the only place I can turn to right now.

My girlfriend is plenty good looking, in fact i'm more physically attracted to her than any girl i've ever known. That's why I consider this a problem, because I really shouldn't have a need to look at these things anymore. But when i'm on here and I see the ecchi board or something, I go on autopilot and can't stop myself. And to answer your question, it's mainly ecchi right now. As I said before, i've managed to back away from regular porn and hentai, but then again I slip up when I see it.

And no, she doesn't know about it, that's why I feel like i'm being unfaithful to her.