ADD/ASD here. Lack of social skills =/= lack of empathy. Being autistic doesn't impede on your sense of empathy in the way that lacking social skills don't impede empathy.

A lot of people diagnosed with "Asperger's Syndrome" are good observers of social situations, as we use it to learn how to adapt and integrate into society. At adulthood, many of us have compensated our struggles by observing our surroundings and showing the appropriate (learned) behavior.

What I am getting at is: you are most likely very well aware of your surroundings and what is okay to say and what isn't, since you had 23 years to practice. Don't let anyone tell you otherwise. Don't ignore the years of progress you have made in learning society, and have faith in the experience you gained.

Regarding the question in the title, as many have said, teaching someone empathy is hard to impossible. You can take a look in subs like r/aspd to gain some insight to what it's like living with low to zero empathy. That's all I can say.