Why does my husband constantly talk about the size of hos manhood? ?

Its not like he should even be concerned. I think its too big but why does he keep asking me. Is he hyping up his ego or is it for someone else? We have been married for 2 years and have a baby together. Also I caught him doing sex chat on his cellphone with multiple women. They were even saved in his phonebook under his sisters name. What should I do?