Hi Velvet,
I totally sympathise with you. I had ms with my son from weeks 7 to 25 and it was awful, but for some reason with the passage of time (he's 3 now) I persuaded myself it wasn't really that bad, that every pregnancy is different and that I might not be sick much at all this time.
Needless to say, this time the nausea kicked in at week 5 and was awful. I was off work between weeks 12 and 20 as I literally couldnt' do anything (I share your excess saliva (i needed a spit bucket next to me for months) and horrible taste in my mouth, which with my son lasted throughout my pregnancy).
I normally work mornings and pick up my son at 1pm (20 minute walk). I managed up to week 12 when I just simply wasn't capable of looking after him, and I had to put him in full-time childcare, and the guilt was tremendous (even now I think how this pregnancy has cost me 2 months of playing/looking after my son).
My DH functioned as a single parent during those months (talking made me sick so I couldn't even read him a bednight story).
Even now (nearly 23 weeks) I'm still not back to normal, but am getting my son dropped off at 3pm, and hope to add some 1pm finishes in (but it's the 20 minute walk I can't face). But the sickness is only once every 4/5 days, the excess saliva has gone and at last, I can drink water (found it difficult to keep liquids down).
I just wanted to say, I totally share your misery, and I found it much much harder to deal with this time round than last time, but for me it hasn't lasted forevcer, it does end and you will be back to functioning normally.
Do you have anyone nearby that could look after your son in the afternoons to give you and OH a break? I was lucky in having a flexible childminder (as we have no family close by) and I couldnt' have coped otherwise.
I'm so sorry you're feeling so bad, and I have no miraculous cures, I just wanted to send you sympathy and hugs!