Wedding etiquette: What should we do?

My husband and I have RSVP’ed yes to a wedding. It’s a 4pm Friday wedding.
Originally, we weren’t sure if we’d bring our youngest, who is now almost 12 weeks old, but we decided we needed a night out together so we asked our babysitter (my parents): they said yes.

Well, now they say they have work til 430, so obviously we can’t make the wedding itself.
We have a couple options:
1— We both wait and just attend the reception.
2— My husband goes to the wedding, then picks me up for the reception (when we will have a sitter)
3-Possibly find someone else to watch the kids but it’s very short notice!

It is my husbands cousins wedding, we both aren’t even too thrilled about going. My husband will be losing out on money at work and we have to shell out money for a gift (not like they ever gave us anything for getting married, nor their parents…/vent.)
What should we do?