Aww hun, I feel your pain - this is HG pregnancy #4 for me and it's been by far the most evil of the lot
In terms of support groups, I find the HelpHER forums (www.hyperemesis.org) are a great source of support, so many people who just 'get it' in one place.
Treatment-wise, there are other things you can discuss with your doc that might help give you some relief. In addition to the three meds you're already taking, other options include high dose VitB6, phenargan and stematil (which can be given as a suppository if you can't keep it down). The ranitidine has been a huge help for me too, it doesn't have any effect on the nausea, but it reduces the acid so makes vomiting less painful and minimizes the damage to your oesophagus from vomiting.
Are you taking the odansetron as wafers or tablets? I started on wafers as I couldn't keep the tablets down, but now the taste of them triggers nausea associations so I've switched to the tablets.
As for feeling detached from the pregnancy, honey, you are not alone and it doesn't make you a bad person! In the early days of this pregnancy, I desperately wanted someone to suggest termination just to give me an 'out' clause coz I was so desperate to be well again. By 30 weeks I was praying she'd be born early coz the thought of weeks in NICU was far more attractive than another ten weeks of HG. Even now when I'm less than 10 days away from induction, I don't think I'll really feel bonded with this baby until I can hold her in my arms. But I do know from having survived this horrible disease before that once she is here, it will all be worth it.
Hang in there, but definitely have a chat to your doc/midwife about other treatments, and maybe even request a referral to an OB who is knowledgeable about HG. And focus on the small milestones - thinking '26 weeks to go' is pretty overwhelming, but if you break it down into smaller chunks (next u/s, next midwife appt, 20 weeks, 24 weeks) etc. it can seem less daunting.