OP I hope you have got home, got warm and got a cup of tea.
I'm so sorry to hear about your MC's
I have had 5 on the run too, so I have an inkling about what it does to you 
How is your relationship with DH generally?
"think part of the problem is that a guy I'd never met before was nicer to me than dp was" this is a bit of a worry, isn't it.
Would you say your DH is a good man who is struggling to cope, or would you not think that?
"With each MC he's gets more distant, then when the worst is over he carrys on as normal and is lovely again."
Perhaps this is just his very shit way of coping? I think often the DH feels they have to soldier on, but can't really cope to do so.
You know you shouldn't have slapped him, just as you know he shouldn't have gone out on the piss, lied and then said a really really horrible goady thing to you. You both need to apologise at some point, and then perhaps admit you aren't coping with the amount of pain you have to carry?
Perhaps you could look into some counselling? I am having some at the moment and it is really helping.
I decided that the outcome I could cope with least was to end up without a baby, so therefore the best course of action for me was to carry on getting pregnant (and losing them) as often as I could in the time I have left to conceive. (I know other women might reach entirely different decisions and decide to stop or have a break for a while, not trying to say my way was right, only that it was right for me iyswim)
But this course of action has meant no real time to grieve or recover mentally. What I am dealing with in the counselling is the fact that all that grief and loss is still there and needs to come out. My DH has thrown himself into his work, partly by necessity as I am hardly bringing any income in, and partly to distract himself, I think, but he is now realising that he also needs some help in this regard.
You are NOT an awful person.