I found out my ex-wife was having an affair with her boss witch I knew him and he know that we were married. As a direct result of her and his actions, I became stress and depress, I got medical attention but I end up losing my job because I couldn't concentrate on doing my job. Also, as I found out about the fair, and I left the house, within 30 days, she tried to cohabitate with her boss/boyfriend causing a tremendous stress on my older son and now he is emotionally stress because of it. He also got medical attention via a psychiatric.
Can I sue my ex-wife and her boyfriend for emotional distress for me and my son and also for loss of income, because I lost my job for 9 months due to the emotional distress they put me throw?

Where? No, you cannot sue her boyfriend in "most" States - if you are in the US.

She made promises to you. He did not. SHE caused your heartache. I'd be angry with her, not him.

Depends on where you are - but, in general, no, you cannot sue your spouse for causing you (and/or your son) emotional stress.

It depends on your state. There are a few states that do allow you to sue for alienation of affection. If it's allowed in your state, it would involve a trial that would delve into the history of your marriage, your work, and your relationship with your children. A trial would be stressful and costly to you and your ex-husband.

No, you can not sue for the loss of your job and for other losses. While they may have been a cause, most people learn to deal with it, and still can function in life. Or get help before it gets that bad.

You sue for divorce and property settlement

As always, wonder why I got a "dislike" for posting the law. Anyway, the States that DO allow alienation of affection lawsuits are: Hawaii, Illinois, Mississippi, New Mexico, North Carolina, South Dakota, and Utah. In all three the Plaintiff (person who sues) PROVES that the Defenant (the person who is sued) left the marriage SOLELY because of the actions of the new love interest, not because the Plaintiff is or was a bad marital partner. You can imagine what a circus that turns into.

If you look at case law very few of theses cases are successul - expensive, hard to prove, and the Plaintiff's entire history comes out.

The usual argument against the lawsuit is the instability of the marital partner.

In this case OP LEFT the house (his words). He abandoned HER. That will add some spice to the trial, too.