I would be willing to bet that all of your friends that want you to "get over it" have never had to go through this situation.
You are mourning the loss of your baby, even more so you are doing it in secret - without the support of your significant other, becuase he never knew in the first place. That is a tremendously hard thing to do!
It is going to take you time to get over this. Just physically, your body is going through changes adjusting from being pregnant to not-pregnant; your hormones are shifting around wildly (AGAIN!) That is enough by itself to cause depression. And I would be willing to bet that you were feeling a bit worried about this baby, since you hadn't told your boyfiend, so you are probably carrying around some guilt (or relief, or guilt from relief) - that you may not have even recognized because it's buried deep down.
Miscarriages are hard enough when they happen in a "traditional" marriage, where the support structure is (supposedly) setup, although this doesn't always help as much as people think. But it can be especially tough on someone who is single and living the free life and is just expected to get back into the swing of things.
If your friends aren't willing to accept the emotional answers, then give them the physical ones - maybe that will cool their heels some. And in the meantime, think about possibly talking to you OB/GYN about either some counseling or possible post-partum depression. It may not be that serious; but it's better to head off the worst scenario, than to find yourself in a really bad place 6 months from now.
Hugs, <img src="/images/graemlins/heart.gif" alt="" />