How do you forgive and move on from hurtful behavior by in-laws while still protecting yourself from future issues?

Should I divorce my husband who is emotionally distant, unfaithful, and lives apart from me, but provides some financial support, or try to work on our marriage for the sake of our three children?
My ex who left me 5 years ago got married and is having a baby. I am crushed and although we don't communicate, I am still unable to let go. Any suggestions?