Send a Letter of Apology

The old term for it is "eating a little crow" or "eating ones hat." As you are unwelcome at their house, a letter of apology is the indicated method of apology. My sense is that they will not accept the letter or the apology, but clearing off our side of the street is all we can do to make amends to those we have hurt. If the apology is not accepted that's the best you can reasonably do then the problem is theirs not yours.

He Needs To Apologize

My opinion though is that it was rather tacky of your friend to tell his parents of the words said in anger. Perhaps an apology is needed from this sector?

He Needs To Make a Choice

One question you perhaps need to discuss with your friend though. Who do you both intend to spend the rest of your life with, the parents or each other? If he chooses to be swayed by his parents, no matter what the reason, you can never win that battle – don't even try, only resentments stem from that kind of situation.

I was told that if I married out of my faith I would be written out of the will. I did and I was. My parents did not like my wife to be and I had to make a choice. I did and never looked back and I was not sorry for my choice.

You guys need to sit and make a decision, for better or for worse and move forward.