It's really frustrating to think of what's happened to Denny in the short time you've owned him and tho I never would have wanted to say anything in the past. I also think you over paid for that guy which is another unfortunate situation tho I know had he not hurt himself, even with the market the way it's been, I think you could have sold him for a good buck after putting training on him.
As for the friesian situation...Life changes alllll the time. You have you dreams and goals, things you think about regularly, things that may or may not happen but that's why they are called dreams. Sometimes those dreams do come around the corner and come true. When those happen, they do affect your life and the way you are currently running things. Sometimes you have to re-adjust your life and your long term goals and plans and I think that's what happening assuming you are getting a friesian.
I think it's an interesting topic, because I just went thru the exact same thing about 2 month ago. I had Calypso, my draft cross which I adored and I had these plans for her but then one day out of the blue, Cobalt came into the equasion. That affected EVERYTHING. As soon as I wrote out that cheque I knew my life was going to change.
For me selling Calypso, tho it was very hard(because I had made out all the plans and goals for her)to sell her, was the best decision I have ever made. I own the dream horse I have always wanted to own and I am able to focus 120% on him. Every penny I spend is on him, his tack, his gear, his training. Every moment I spend at the barn is with him. My focus is 100% on him and will always be so. I think once you own a horse of good caliber you can't do anything but focus on him/her. You have spent a lifetime dreaming and wishing you could be in the situation you are in so when it happens YOU HAVE to be there all the way.
I don't think it's being selfish at all with Denny. You gave him a great home and good care and the situation changed. All it means to him is that someone else is going to be caring for him and feeding him. If you were sending him over to the meat packers or a really bad home then I would think your decision were a selfish one but it wouldnt be the case. As to what you should do with him? I think regardless of the age of the new horse you get (rideable yet or not) seeling Denny would be the best option as it would allow to focus on your new show horse 100%. Now the decision is going to be hard because its finding the right home for him because he is injured and green. A temporary solution might be to lease him or post him for a quick sale as it would allow you to quickl focus on the one horse AND put you in a situation where you can find him the right home.
I hope it helped. You know how to get a hold of me if you want my advice
Good luck with your chat with your papa keep us posted.