[DH posting]
firstly, OP, i would tend to be of the opinion that the amount of pain you describe should warrant being signed off work for the forseeable, regardless of pregnancy.
Secondly, whilst I concede that it's often difficult for us mere men to understand, whats not to get about pregnancy? your body is going through massive changes in order to grow a tiny human, often pushing itself to (or past) it's own limits. imo it goes without saying that there are going to be unpleasant and painful bits, and as evereyones body is different, experiences and levels of pain will vary.
I do not claim to be super-hubby, far from it ~(I'm sure gemjar will be quick to agree) but I at least can be supportive and understanding. It's a 2 way street though, I often feel like I've got several size 8 knitting needles jammed in my shoulder socket due to an injury and I get sympathy when that's bad, why shouldn't my other half get the same if she feels crap?
I think it's already been established that your hubby has been insensitive, and even I am a little taken aback at the level of it. However, I can say from experience that it can be incredibly frustrating being on our side of things, as there's often little or nothing we can do to be of help or comfort, and that feeling of uselessness is far from good for the self esteem. If your other half has been listening to you complain (and rightly so) about your ailments it's reasonable for him to feel increasingly bad about himself, leading to him sub-consciously trying to prop up his ego (leading to dumb comment). I'm not excusing it, just saying that I can understand the possible reasons behind it.
As for the useless sperm donor comment - beyond harsh. A child should be the result of a loving, caring relationship, if you truly believe that comment then your child clearly is not and you should think about splitting up. I would be genuinely devastated if gemjar saaid something like that to me.