How can you forgive and forget when a spouse has had several and is still having emotional affair's?

I found out about 15 months ago that my spouse has been engaging in many phone calls with certain women one in which was supposed to be my friend of 30 yrs. The other women were women that he works with. He would lie and hid his phone and the phone bill when asked who he was talking to. Even to the lady that I have known for 30 yrs. I have discovered that his lies has caused me not to trust him. We have been married for 30+ years and I feel I do not know the man I married.