These are definitely hard things to tell a boyfriend, for sure. I was abused and molested as a child, and I've told a couple of boyfriends. I prefer to break it up into multiple conversations and let things come up naturally. I tell about general family dysfunction and the like first. If that goes well, I might then (another day) mention that I was abused. I may or may not bring up PTSD in the same conversation. Further details come if he asks, or otherwise when it comes up naturally and I feel like sharing. Keep in mind that trauma is hard to hear about. Someone who cares about you isn't going to be scared away, but they might hurt on your behalf, and they may need time to process it. They may or may not want to talk it over with a third party (someone who cares about you will be smart about who that is, so try to trust him and don't feel hurt or betrayed).
Use this as a test and as a trust building tool, but don't rush it. You aren't obligated to tell more than you're comfortable telling, and he won't be able to handle too much detail all at once. You also don't have to tell him everything right now.
If you're showing lots of symptoms or something around him, then it might be a good idea to let him in a little, but don't feel pressured to share too much too fast.
Now, you said you've never been in a relationship before, it's been two weeks and you know he's the one? I'm glad you've found someone you care about, but please be careful. If you've never dated before, then you have nothing to compare this person and this relationship to. He may be the one, or he may not. Enjoy this, but don't rush. It took me many years and several relationships (some as long as 3 years) before I found the one. I thought 2 others were the one, including my first, but now that I had those experiences, now I actually know. I have experiences to compare to. I'm not saying your first has to fail, because some last forever, I'm just saying recognize your lack of experience and take it slow.
Good luck!