Understandable prisoner I'm glad you have had it changed.
Would some form of counselling help if you have previous da and struggle to trust?
I would suggest (based on nothin but instinct) just try each day to share something you are feeling with DH - a wish, a concern, a dream, anything really. Try and put in place plans for your labour and the first few weeks which are going to protect you. E.g. How do you intend to feed baby and how can DH be part of that, what sort of visiting are you happy with etc.
Pregnancy is a huge loss of control and getting some of that back can really help.
As for your bladder infection, I'm glad that has been diagnosed and presumably treated - I think if your physical symptoms abate slightly it will help you to deal with the rest.
You can't get sacked for going off sick - and I believe that once you have had your April and May pay, you have qualified for maternity. Consider going on sick leave for May if you get full pay, June onwards if not. I. Sure your doctors will sign you off.
As for the horse - if this is PFB you have no idea how the next few years will pan out. Some babies are very very easy, and if you have an easy birth you could be back riding within a month. Pregnancy is not the time to make life changing decisions, and I assume you have only been trying to find a share for the past 16/20 weeks? Give this one some time, figure out a way to get through the next 26 ish weeks, and go from there.
I really hope things are looking brighter - keep posting for sympathy and advice if needed, you will find it here.
Congratulations on baby - you will look back and realise it was all worth it (so much so you will probably do it all again!) x