Okay, how about "your leg use to be broken but I can see where it is healing nicely now". Would you take offense that your leg use to be broken?

How about, you use to be angry all the time but now you are often really pleasant to be around.

It's an observation. He use to not understand you and now he does. That goes both ways; you use to not make sense but now you appear to! You are learning to talk sense! Your negative condition is not permanent, we just need to learn through therapy what we weren't taught by our parents/surroundings growing up! You had really crummy teachers and now you have a better school with better teachers!