@bootsnjeans,
So many issues here that it makes it quite complex. This is not a simple relationship issue..as a lot is at stake.
I have one key question:
is the biological father going to contribute financially to the child's welfare...birth ..hospitalization...after the baby is born? What significant role will the biological father offer his help? Is his concern genuine and will it extend past the next few months?
If the answer is none at all, then be civil and just tell him no. Your heart is already connected to your ex-and-now present love. This man, biological dad, will soon fade off. He might be doing this out of guilt which is pushing him forward. that guilt will fade off.
If he is genuinely wanting to be involved long term ('til age 21), then by all means invite him to attend. But this guilt, is something that you can't respond for the long-lasting good for the child's welfare.
I suspect he's just mouthing the right words. You can advise him to just focus his energy elsewhere. It seems to me that the time for the relationship is in the past with no chance for revival.
Lastly, forgawdsake ... use some form of EFFECTIVE birth control.