Your first ten moves were good and your opponent's were very poor, but you shouldn't let that deceive you. You seem to think that from move 14 to move 43, you and your opponent divided the board in two, so that rows 1-6 are "his territory" and rows 7-19 are "your territory". On the contrary! You have given him 6th line territory in exchange for a 7th line wall which will influence fighting in the center. In general, this is very bad; even a 5th line wall (facing the center) in exchange for 4th line territory (on the side) is usually considered to be favorable for the territorial player.

But lo! Your opponent starts trying to make a living group with the K10 stone, right next to your wall. You think that he has successfully "dug into" your territory, and are afraid that this invasion will be a "success"; but that's misleading. It wasn't your territory to begin with, it was an area where you had lots of influence, and you should have been overjoyed that White wanted to start a contact fight there, of all places, where the fight benefits you the most. White made a huge mistake, and this was the only that you could take such a high wall and make a profit out of it. Look at all the territory that you built up while he was floundering around with the weak K10 group; the entire left side, the entire top side.

In general, your 8-stone wall on the seventh line would yield maybe 24 points (people estimate 2-3 points per stone), while his 8-stone wall on the sixth line would yield 40 points. But because he immediately tried to start a fight in your zone of influence, you turned the wall into about 80 points.