Hello msgrace, and welcome to a2k
Your husband has been lying for 13 years about what? Him watching porn?
Perhaps, if you can pinpoint what he's lying about it would help you
understand the "why".
On the other hand, you have distanced yourself from your husband
physically and emotionally which makes me wonder why you are still
married to him, if you're indifferent towards him. Why stay in a loveless
marriage? Just for the kids? What are you teaching them? That having
no love in your life is okay? Don't you think they realize what is going
on between Mommy and Daddy? Think again!!
If you want to save your marriage, I suggest counseling for the both
of you and hopefully you both can learn to walk towards each other
again. Good luck to you!