I have to say, regardless of the horses 'reasons' ( physical or mental, emotional) You did not get the horse you are in need of, and it is absolutely OK to say, I want a different horse! It is not up to you at this stage of the game to have to figure out what is upsetting the horse. You have an agenda of your own, pass her on to someone who is ready to work with her, You are looking for a teacher, not a boxing coach! When you are more relaxed, and have the experiences under your belt, you can look at the next head tosser, and wonder about the saddle, or neck pain, right now, your safety is more of the issue, not to mention the horses safety! There is a reason 'getting back on the horse' is an expression for doing something difficult! Dont let yourself get taken there! I did everything in my power to make sure my students (and myself) never hit the ground or were scared to that point until they were good enuff that they probably wouldnt hit the ground! That means choosing your mounts carefully!
In my opinion, the first problem is that you bought a MARE. (sorry, they drive me nuts!) Just like in any chicken coop, or ANY social structure for that matter, there is a drive in SOME animals to be the lead animal. I have found it is stronger in some mares than others. The whole 'I dont want to leave the house area' ride, and the anxiety colic she had when your hubby made her go, are pretty clear signs.
You are trying to build confidence, and have stated (wisely) that you are afraid of horses. Ditch the mare. Leave Hubby at home. And go get that bomb proof horse that will take care of you! Hubby may not want a horse that he will get bored with over time, BUT YOU DO! It takes time for that confidence to be built, and to become real, Its nice to look forward to a good ride, on a good horse. It is no fun to always have in the back of your mind the question 'is this horse gonna dump me now?'
Been there, done that. Life is too short, and there are too many really nice horses out there that want to go with you, want to have the fun of a cattle farm, WANT to leave the house area with YOU! Ditch the @#$%, and go get a fun horse! If your hubby wants to work with her, great, but she is clearly not the horse you wanted.
Before you buy, if you dont get that 'gut' vibe that signals the instinctual 'connection', that can and should be there, then hes not the right horse either! They often pick us as much as we pick them!
Heck if you were closer, I would give you one of ours!
Sorry for the long rant, I hope it doesnt come off too pushy or bossy, its just that I feel very strongly about matching horses to riders. Let a young horse learn they can toss a rider they dont like, and they try it again and again! It can be just as bad for both horse and rider. Please accept this as just my opinions, and in the spirit of advice in which it was offered!
Good luck, and take your time!