I don't think anyone was chiding you, everyone agonizes over chopping down a tree. It's definitely frustrating when you realize your walnut tree is 'the wrong one.'
Cruel irony dictates that this pecan tree must go. For some reason this yard doesn't have what I thought was the required pecan tree, except this, which can't be allowed to stay that close to the wall.
If you search "bradford pear invasive" you'll find tons of 'bad press.'
Ohio department of natural resources:
http://ohiodnr.com/LinkClick.a...
Ohio invasive pest council:
http://www.oipc.info/Conferenc...
US Forest service:
http://www.na.fs.fed.us/fhp/in...
National parks service:
http://www.nps.gov/plants/alie...
A thorough article in Bioscience magazine:
http://mipn.org/Callery%20pear...
Did you look into redbud trees at all? There are indeed a glut of pics of baby trees, and hard to find pics of fully leafed out mature trees grown without unnatural pruning, but they get 30 feet tall, with a very dense canopy, probably providing more privacy than you had from the walnut, branching out well above the ground, making it possible to drive or walk under them easily. The last redbud sprout my Mom relocated in her yard got taller than her house the 3rd year. It's a 1-story house, but on an uneven lot, so the roof is about 15 feet at that end. The trick is to find a nursery tree that hasn't been pollarded to branch out a an unusually low height. You might still not like it, but it fits the requirements you described.
I'm sorry you're so frustrated! Your story is worth a few acorns, although I wouldn't recommend starting an oak tree there!