people get so caught up in the present that they forget people who have left, my dad experienced the same thing when he retired from work, things will get better once the baby is born (at least you will be able to drive again)
If you cant get about why not keep in touch via the phone or email/ facebook, its only for a short time. I can understand how you feel and its quite miserable, maybe you should mention how you feel to a good friend, maybe they dont realise that they are making you feel this way?