When you describe people by saying they probably have this, that, or the other psych diagnosis, you convey way more about yourself, than you do about them.

It isn't much of an apology to send the message that, "I'm really sorry that I told you the truth about what an awful person you are."

This would be better: "I'm sorry that I made comments on your relationship with your boyfriend, which I'm not now, nor ever was, in a position to make judgements about. No one knows what goes on behind closed doors in an intimate relationship. What people see can be the tip of the iceberg, and I was completely out of line to be talking about what did, or didn't, cause the relationship to fail. I did get uncomfortable when two of you were having a spat, while I was there. I should have just gone for a walk and let you two have your privacy."