Getting pregnant and having a child affects men and women differently. Although it may have been hurtful during your pregnancy that he would not have sex with you, it's quite likely he had little fear of poking that little creature growing inside of you - wink, wink :).
But - Now it's up to you to take control of your sex life. Surprise him with sexy lingerie, plan a surprise night out and arrange for your child to be watched by a family member - even if it's for an hour. It's very difficult for some couples to make time for romance and intimacy after having a child. But, it's IMPORTANT. Yes, it can be stressful for both of you to adjust to your new exciting life, but isn't getting off an easy way to alleviate that stress? Just saying...
Stop talking about his lack of intimacy with him and take control. I know you have a lot on your plate, but it's up to you to bring back the romance.
And, NO - at this point I'm not convinced he's cheating on you.
P.S. Congrats on your new bundle of joy!
Corn
Love 
