Having been of the receiving end a couple of times, the most lasting damage done by cheating isn't the sex. It's the deception. The amount of lying it takes to carry on an affair is just astronomical. They lie about everything. They have to. Your life becomes a lie. Similarly, the amount of deception needed to carry on an addiction is impressive. I think you should sit him down and tell him what all this lying has done to you. Explain that you are supportive of him quitting and getting into nicotine/vaping recovery. But the lying has got to stop, if he wants to be with you. If you don't do this and if he continues on the way he currently is, it is only going to get worse for you.

One constant with all addicts is that they never realize just how bad their situation really is. They think everything's fine. You need to make it very clear that everything is not fine. You have to take care of yourself. I wish you all the best.