You have bigger issues to deal with than wondering whether your husband and this woman are more than friends. You also seem to think that if you could get this woman out of your life that all would be fine. Not so. The woman is just a symptom of your marital problems. The real issue here is how your husband is behaving toward you.
The woman may have told him to lie to you, but he's a big boy and he lied to you all by himself. He is behaving in a sneaky and hostile way toward you. If this woman is simply a friend, then why is he calling her from his truck when you aren't around and why is he lying to you about her calls? It sounds like he is putting her feelings and wishes over yours. Does he care how you feel?
If you've been reading my columns for a while, you know when one spouse cheats on another it's an act of aggression against his/her partner. He may not actually be cheating on you, but he is using this 'friendship' like a club and beating you over the head with it. His behavior is hostile and inconsiderate. He dangles this woman in front of your nose and behaves like he doesn't care at all about how you feel.
Such hostile behavior needs to be addressed directly. You need to tell that the only reason for him to be so mean to you is because he's angry with you. Ask him what you said or did to make him so angry at you. Ask him what he gets from the friendship with her that you aren't giving him. Being responsive to what he tells you is key to saving your marriage. If, for example, he says that this woman makes him feel special, then he's telling you that you aren't making him feel special anymore. If you work to reintroduce into your marriage the thinks that he gets from this woman, he should be willing to let her go on his own. If he won't open up to you, then go to couples therapy and get him talking, not acting out his anger through this friendship.
Don't put your energy into trying to rid yourself of this woman. She is merely a messenger, an angel in disguise, warning you that the marriage is in trouble. Getting him to talk about his anger toward you and working to fix what's troubling him with you and the marriage is your key. When he feels happier with you, she should fall from his life the way a dead pear drops from the vine.