Yuck! What a situation.... cheaters are cowards. Cowards get my pity, and there is no more emotion I hate giving than pity! yes, he is trying to focus your attention on something else (the new puppy) and off of him. A distraction so to speak so you won't have time to check on his activity, or lull you back into unawareness of his activity!
Maybe he did it to make you feel like you'd be even MORE financially unstable if you kicked his sorry A$$ out, to make you think twice about that. Either way, he certainly did put you in a bind here. He sounds very selfish.
I am not married, nor have I ever been. I was with a guy for 10 years that I probably would have been able to look the other way and forgive him if he cheated on me because I was completely and foolishly in love sooo much with the guy. He was a tool, but not a cheater as far as I know. We did end up breaking up 5 years ago and selling the house and canceling the wedding and all that fun stuff. I know its hard to leave someone you love, I had to do that, it nearly killed me to let him go. In the end though, you won't feel like you 'wasted' so much of YOUR time with someone who was never going to change. Tell him you want texting removed from his phone and see what he says, whether you do it or not, you'll get the idea how much 'these girls' mean to him by his reaction to that.
If you don't want to leave him, then counseling sounds like a MUST for HIM. He is very selfish and narcissistic and those qualities need to be fixed.