While I agree with the comments from many of the posters - I disagree that you should just take it for granted that you were invited.
You say the wedding is five hours away - then it’ll cost you to make the trip. So like some of the others have said, call before hand, congratulate them on the upcoming wedding - IF they extend an invitation during the call - go to the wedding - it’ll make your husband happy. But, if they’ve not invited you yet and don’t make an effort during the call, I would feel like a bin-bulaya mehmaan.
There is NO excuse for not inviting you when your call gives them a chance to make up for their oversight. Quite frankly, when there is a wedding (in the family or for a friend of) - I’m less concerned with the formal invite, I’d rather get a call to tell me 1) guess what I’m/he’s/she’s getting married and 2) keep this day free because we want you to come.
You guys live 5 hours away - you’ve got to make travel and accomodation plans - your host shouldn’t take this for granted and you need notice to do so. It’s common courtesy.
My cousin invited me to the nikkah and not to the church ceremony - it was not an unintentional oversight - they explained later - they were trying to save on costs.