I have no idea how experienced you are with horses, so please don't be offended. I'm a pretty new horse owner myself and even though I think it would be a very good idea to have a trainer work with both you and your horse, I think it would also be helpful for you to get some books or videos on training that support what the trainer does. I was clueless when I started this and have found it helpful to read lots of books on training to understand why trainers do this or that with a horse. That way I won't undo any training they have done.
That being said, if you are miserable and won't enjoy training him and working with him until he has the kind of manners you want, there is nothing wrong with finding him a good home with someone who is willing to work with him and finding yourself a horse more to your level of experience. If you will be nothing but frustrated while working with him, you will neither one be very happy.
I was normal...then I got a horse.