I could be off, but this is what I see....

1) Your dad does not just have a farm.  He has an AgroEntertainment business which involves horses.  This business involves a fair amount (or reasonable amount) of interaction with the public.

2) Your wife may not be wired to work well with the public.

3) When you met your wife, you and her talked about having a farm. Maybe you and your wife need to sit down and clarify what that means - what does that farm look like? I suspect your definition of a farm and her definition of a farm may not be the same.

Your first obligation is to your wife.  You and your wife need to have a serious discussion if this is really what both of you want.  If you are not in agreement, maybe you - both of you - need to keep your day jobs, and pass on taking over this business. 

Maybe what your wife really envisions is a small property where you can houses a couple of horses for personal pleasure riding, and not be running a agro-entertainment business. If that is what she desires, maybe you and your wife need to look around for a small property that meets that expectation, and let this one pass.

That is what I see.