I really would advocate that you sit down and talk with her about this - and then go and see an independent organisation like Relate.
A baby brings huge changes and responsibilities to a woman, and if she is doing all the work while you troll around on dating sites and watching porn, how do you think that makes her feel? Worthless, that's how - the father of her child prefers cyber-sex to her. She can't help how she feels during her period, many women have a vile time about that time.
You have to make the effort - this isn't about you, it's about your wife. Make her feel loved, spoil her, help her. Move back into your bed if she agrees - no sex, just cuddles. I wouldn't want to be with a bloke who spends his time the way you do. Stop the porn, delete the link to the dating sites. Be responsible, your self-esteem will return.