No! No, no, no, no.
Hun, don't do this. It will make me sad.
First off, he has a girlfriend. And, well, that automatically means, you should back off. While he is still with her, he's hers. What do you think would happen if she found it? I don't think that be too good.
Second of all, all of this sounds a bit skeptical to me. No offense. You may want to make sure of things. I don't think he's being totally honest with you, I think he may just want a naughty picture from you and decided he should lie and say he's had feelings for you. Like I said, no offense, and I'm not saying this is true, I am simply stating that this may be the case, and that would basically . . . suck.
Third of all, if you are a minor, or he is, then it's against the law to send really naughty pictures. But from what I can see, I can't really tell if you're a minor, I don't think you are . . . but if you are, remember that, because if you're a minor and he gets caught with that picture, I know that you will be registered as a sex offender, and he probably will, too. Same, if he's a minor and you're an adult, same deal.
So, what I think you should do, is . . . before you do anything rational, see if he will dump his girlfriend for you. If he's really had these feelings for such a long time and still feels for you in that way, then he will! And if this happens--and neither of you are minors--uh, sure, send as many naughty pictures as you want! (:.
If he doesn't dump her, then, well, ya know that he's a liar, and if he doesn't dump her, you'll also be glad you didn't fall for his trap and let him deem you his hoe or *****.
Good luck with this, sweetie. I hope it turns out great.
(:.