This man took pictures of me undressing.

Okay, this is a serious situation. This guy is breaking the law on two fronts.
1. That's underage pornography.
2. That's blackmail.
Both of those can get the slimy creep thrown in jail for a decent amount of time. Personally I say go for the sex offender list and get him in jail for that count. I guarantee that that'll shut him up and give him the life he seems eager for. If he's underage too, that's a little more difficult for me to say as I'm in South Africa, not USA.

Okay, as for what you can do now, perhaps you can invite someone to eaves-drop on your conversation so that it isn't just your word against his. Try a teacher as it will add to the influence that you can use. Don't even think about going out with this guy, at any cost. He obviously didn't respect you before, and I doubt he will start. What kind of relationship does he expect to start from blackmail, anyway? A loving one? You should ask him that.

It's good that you want to remain with your boyfriend only. This other guy doesn't deserve you. How on Earth did he get pictures of you undressing in the first place? It may be a little more complicated if you knew he was doing it, but as I doubt it, and it was likely a peeping tom, he stands to lose quite a bit too. I really dislike pervs like that. Dislike is not quite strong enough a word to use, but you know what I mean.

Anyhoo, I really hope that you can get to the bottom of this and that you'll come out on top. Don't give this guy the chance to ruin your life. Take legal action against him, and seek a teacher's or trusted adult's help NOW. This creep can't be allowed to walk free. Don't give him the chance to push you or any other girl's around any further. Please? This guy really doesn't deserve a chance to talk in the same room as you. A restraining order might be a good thing to add to the mix too.

Anyhoo, I've seen on a couple of other places on this site that you're four months pregnant now. That's excellent. Did you know that your baby has everything that it needs to live with it now, and all it needs is to grow bigger before it'll be able to survive in the outside world? At thirteen weeks, the last of your baby's bones was completely formed, and a doctor can tell you the baby's sex. Have you decided if you're going to find that out yet, or what you'll do once the baby is born? Oh well, sorry for the rambling. I just love this sort of thing, and I even used to teach a life skills class on it to grade eights (sophomore, I think. I'm a South African and we use a different system).

Tell him that you are not only already in a relationship, but you are also pregnant, and this pregnancy will require most of your attention and devotion. If he does not accept this and move on, then you need to report him, perhaps to a school counselor or someone in authority who you are comfortable talking to.

That is sexual harassment! You are also underaged, he can get charged for creating child pornography, and threatening to distribute them! You should talk to your parents, police, and the school! Something needs to be done to put that creep where he belongs.

Omg this is horrible! Go to the police, the school and let them know about this. This is a serious offense. If you are under 18, that is child porn. He needs to go to jail so he can never do this to anyone else.

Tell your boyfriend too so he can be there to stand by and support you. I know you might be embarrassed, but you don't want him to hear about it from anyone else.

Def. Don't go out with the guy. He sounds like a sadistic freak, you can't be his girlfriend. Seriously he's got some screws loose if he thinks this is a good way at getting a date.

God bless & I hope everything works out for you

This is something that should be reported. You should also talk to your "man" and let him know what happened. That way he will know the story from you and not someone else. People should not be bullied into doing anything thing that they don't want to do. Just think, if he did this to you, he might have done this to someone else as well.