If you still love him, like you say you do, then you need to let him go and move on. Allow him to be happy—because he was broken too when you broke up, he just found a way to mend his heart with someone else.
You don’t have to be perfect to be worth loving.
If we don’t see the other woman as an all-powerful, cold-hearted monster who eats in a relationship men and their families for breakfast, we might be able to see that they are just women who are in very painful, very, very bad situations.
I am here to tell you that you will be happy again.