My hubby was in love with a coworker for 4 yrs, now he realizes it was nothing at all, should i forgive him?

Well he thought he was in love and i had no clue at all for these 4 years, the woman wanted nothing to do with him from the onstart but my hubby had his hopes and even told her that he thinks he is in love with her. Their contact so what i was told was minimal, very light conversations, nothing in depth. They never hung out, never spoke on the phone and never emailed in the past just simple messages on Facebook in the last few months. How i found out about the situation was when he connected with her on Facebook and sent her a message "I miss you" but after that she cut him off as a friend on FB and that is what led to my inquiry. By the way, he has left to a different work location so he no longer sees her, that is what prompted him to send her that email message after 2 weeks of not seeing her. Now, he realizes that after not seeing her for 2 months and the confrontation of all of this, he genuinely had no feelings for her. but i feel deceived that he thought he was in love with this other woman that number one kept on blowing him off that he barely knew, and that he was foolishly infatuated with her. we have our marital problems but this all started when we bought a house and had a kid so he was looking to escape from all of life's complications but i feel like this is emotional cheating and worse of all he said he did nothing wrong and that i deserved it for being a nag. he is not even apologetic he said he didnt do anything but i felt that for 4 years he had pledged his heart to someone else that he didnt even really know. This woman even told him that you dont even know the other side of me. In his mind he painted a picture of this woman as being perfect but he doesnt even know what her background is, what her likes and dislikes are, if she has siblings, etc. He fell in love with his fictitious creation. And the worse part of it all is that he got carried away and told her that he thinks he is in love with her, she just told him go home to your wife. I am having a hard time blowing this off especially without an apology from him. Is he thinking that this was no big deal cause nothing truly happened on a physical level and it was strictly one sided infatuation. But for him to think that he loved her all this time until it all came out in the open kils me, what if i had never inquired about that message, he would have thought that this was the one woman he missed out on. I know this term of escapism he sufferes from anxiety and panic disorder and does not like to confront every day issues, any advice???