Semperfi. Well done. It might take persistence - but there again persistence is all. And it is worth it.
The choice of your husband's rock steady horse is good - leave the pretty 5 yo Haflinger for a bit - she'll survive OK until you are ready for her.
Plan a slow comeback. A little bit each day, every day, starting off in a nice quiet arena. Don't ride if the horse is off colour or on windy days. Lots of walking, a bit of trotting. No cantering until you've built up a few muscles.
You've first got to rebuild the muscles - stomach, lower back, thighs, calves. You've got to sit upright in the saddle and maintain the position. If you have a local Pilates class, that will help you build the muscles away from the horse.
You may, repeat may, have to rebuild your confidence - but to be honest that would not be surprising. You had a seriously nasty fall - for whatever reason.
The biggest problem might be tension. Perhaps, subconciously, you'll stiffen up. Buy a book on the Alexander Technique and read it. Alexander is all about relaxation. Try laying flat on the floor and just let everything go. Relax every day. Pilates if necessary you can also do at home - again by reading a book but its best if you can find an instructor.
Why am I so positive - well after 33 years of riding I came off and made a serious mess of hitting the ground. I am an old man and was lucky to survive. As a result I lost my nerve for riding 12 months ago. I then came off again, several times, because I bought a sprauncy 7 yo skittish mare - big mistake. I had not recognised that I was too tense to ride. The brain said - OI, what are you doing? But with a lot of help from my horsey friends I am back on that same horse and she, God Bless her, is not dumping me these days.
Work with the horse from the ground - so that it gets to know your voice, smell
and body language. Lead the horse in hand before you start to ride it. Get it so that it will walk by your shoulder on the lightest of pressure on the lead rope. When you reckon the horse is ready for your delicate body, then get aboard and ride it in a confined quiet area. Once you are ready to leave the yard, get a friend to walk with you alongside the head of the horse. Take it easy - there is no hurry - is there?
When you are eventually ready for that mad gallop, you'll know - but don't be surprised if you don't get round to galloping for a little while. Time heals.
Remember life without a horse is miserable. That's your goal - to get back up on your very pretty palomino and canter off.
Best of luck