Hun, you know I've always tried to be supportive for you over the past couple of weeks...now I'm gonna be completely honest with you, no matter how bad it sounds.
In regards to your depression (which I hope is getting better), your boyfriend certainly isn't helping matters. You need someone who'll be there and will be supportive, whereas he's never there and has made it clear that he has become annoyed with you because of the symptoms of your depression (which are not your fault by any stretch of the imagination)...now, people like me are here frequently and I've PMed you in the past letting you know that I'd listen to you and try to help you, but of course we're not a physical presence right there beside you. You really need someone there who you can turn to whenever you need to. Having never had a girlfriend myself, I've had to make do with the next best thing - good friends. With one exception, none of them know about my depression, but they can still be there if I feel down, and just being in the company of them takes my mind completely off the depression. While I have supportive friends on various boards I frequent (including TSR), it's just not the same as having a person in front of you that you can talk to.
What I'm about to say may sound a bit cruel, and might not work, but why not just try looking for another guy who CAN be there for you? Maybe just a friend, but you can maybe try and give off the impression to your boyfriend that this friend may be something more. You're paranoid about your boyfriend and this girl he works with, so why not see if it works the other way around? If he really loves you, he won't take you for granted and should try to work harder in the relationship if he sees that he can potentially lose you.....but it's a gamble - I won't put down any of the negative things that could happen, but I'm sure you can work those out for yourself. It's all based on how he perceives things.
Sorry hun, but from things you've said over the past few weeks, I personally have a bit of a low opinion of your boyfriend. Listen to me if you want to, don't listen to me if you don't want to, but that's how I see it.