this will get relocated soon enough.
in the mean time, man up. you made the fucking commitment with your wife when you decided to have a kid.
your post really pisses me off - you are acting unbelievably selfish. obviously, this is my advice, but you should cut off relations with this woman and just talk to your wife about your unhappiness. if things dont progress from that, seek counseling.
do not leave your PREGNANT wife over this woman because you're unhappy, especially when you haven't done anything substantive about it.