Not to rub salt in the wound WWII but now you have no P-51 where as if you had sat back and rethought it you would have had at worst, a p-51 wreck for a diorama.
Part of getting better at all this is not destroying what you've done, because despite what you may have learned by building it the first time, you have nothing to reference back to, nor even nostalgicly look back on to see your improvement, but by looking at the problems you've encountered and troubleshooting what you've done.
Of all the things to mess up, paint is the easist to fix. It can be removed and reshot on your model. Structuraly the model was still sound and can be repainted. Even if you thought you could not have repainted it, there was still the option to use it for other applications. i.e.
-A test bed for new techniques. Paint or structural. Most modelers have one or two that they have relegated to being a guinea pig for something. It has more validity and you learn more by working on a 3 dimensional item than trying out something on a flat piece of styrene.
- Diorama applications. Shot down in the water, hidden in a barn, under a tarp while others are being readied for flight. Attacked on the ground. Crashed. Being scrapped after the war. (one of the most ironic photos I've ever seen was of ex german soldiers and mechanics, destroying allied aircraft after the war for salvage.)
- Salvaged for other parts. You may have a missing part, or ruined a part that you could have salvaged from this bird.
The key is finding the silk purse in the sows ear. I know it doesn't fix the situation now, but look at this as a learning experience. Move on and keep it in mind for future reference. We all stumble a bit before we walk and certainly practice a bit before we run a race. If you find that you are getting frustrated with something, move on. Put it aside. Do something else. You can always come back to it later after gaining more experience or learning a new technique. Besides. Who are you modeling for? Us or you? Despite what it may look like, you must have had some enjoyment while building it and when you first started painting it. Don't compare what you are doing to anyone else here. It is your project and not for us to judge you or your build for it. (There are other venues for that and a whole different thread). We are capricious with ourselves and with what we perceive as aestheticly pleasing. Some like heavy weathering, others like factory new. Some build from the box, others heavily detail. Allied, Axis, modern, WW2, aircraft, armor, civilian, figures...It is what interests them and what drives them and their creative whim.
gderue put it best, in that we often are too hard on ourselves. I will add that our expectations sometimes exceed our abilities and we set ourselves up for a fall. There is no need to. Enjoy what you build, regardless of what you fear anyone may think. Again, it is not for us or them, it is for you.
Good luck, and go out and buy another one. Once more into the breech dear friends once more......