Your marriage is fixable if you’re willing to do the work. You sound kind of resigned and sad, but if you do want make some changes, I can help guide you.
First, understand since you’re 37, your wife is 39 and you’ve been married for 15 years and have two children, ages 8 and 10, you all have a lot invested in your family. Second, this problem didn’t happen overnight. So it’s not going to get solved overnight. And third, it’s not one person’s fault. Your challenge (and opportunity) is to figure out your part in this dynamic and change it. So if she’s not telling the truth about things, chances are there’s a reason — she doesn’t want to disappoint you, or she doesn’t want give up something, or maybe she doesn’t want to come to grips with the reality of your relationship. Since you didn’t mention specifics, I can give you the broad strokes — talk to her about what the lies are and why you really the truth — because it promotes intimacy. You mentioned that she’s negative and has “a cold touch” — but you also say that she’s a loving and wonderful mother. Chances are she’s negative and cold because she’s disappointed and unhappy. You both are — so do your part to get the relationship out of the rut it’s in. Take her out, buy her flowers and gifts and try to seduce here again! This is a lot more difficult than it sounds, because you’ve been in a relationship rut for so long, but you have to be patient, take small steps and stay focused on your goal.
I hope that helps.