Q&A How Do I Forgive When it Wasn't a Mistake?

I am struggling with forgiveness. As a Christian I know I should forgive, but what if the betrayal wasn't a mistake? I suspected some form of infidelity at different times during our marriage (mostly in the beginning), but my husband always lied and because I did not have proof I let it go. However, I always stressed that monogamy was a requirement, not an option. Now I am supposed to forgive acts that were not mistakes, but blatant, purposeful acts of betrayal. How does an unfaithful spouse say sorry and expect a betrayed spouse to say I forgive you when the affairs were multiple, intentional, and spanned over several years or for the entire length of the marriage?