@User09876543217
Is this a joke? So your mother in law (and you I guess as you agreed,) decided you were gonna have a massively expensive wedding - at a massively expensive place. And she transferred half the money to you... So she is only paying HALF, when SHE wants this massive wedding for her precious little soldier. 
And then you went to your parents and asked them for the other half without even actually consulting them and asking if an outlandish amount to pay is OK??? Whose idea was this???!? What a horrible thing to do to your parents.
ALSO... Do NOT take a loan out to appease your bloody controlling mother in law. She sounds bloody awful by the way. I hope your DH (to be) always sides with you and not her in life when you're married, coz if not, you're in for a rough ride.
Going back to your actual question ... IMO, it's really grabby and entitled to expect their parents to pay for your wedding. Unless they offer to pay for it, and you know they're properly minted, there's absolutely no way you should expect your parents to pay for your wedding. If they offer and they are NOT wealthy, then say NO. Pay for it yourself FGS.
The bride's family paying for the wedding is a pathetic old 'tradition' that should never have been a thing. Are you also going to stay at home and give up your career and play the little wifey, cooking dinner for your husband and warming his slippers up for him, and taking orders for him? Because a man being the breadwinner and the boss of the household is 'traditional' too.
You're grown ass adults. You're probably going to have a mortgage. You're probably going to have kids. Pay for your own wedding. For the record me and DH paid for ours in its entirety as we could afford it and didn't want to burden our parents, and we are going to pay a third to our DC's weddings... (both of them.) Their partners parents will pay a third - and then they'll pay a third.
Like the other posters who paid for their own wedding on here, Me and DH, invited exactly who we wanted and had exactly the WEDDING we wanted... We only invited 33 people, really close friends and the closest family members ... We did not have the extra 40-ish extended family members we both had that were expecting to come (even though we have fuck all to do with them, see them once or twice a year in passing, and they don't even bother sending Christmas cards.)
The majority of them didn't speak to us for about 5 or 6 years after for not being invited to our wedding. Some never spoke to us again as they were SO enraged at not being invited. It was actually quite a bonus for us to be honest to have these people out of our lives altogether. Acting like you should be invited to a wedding just cause you're loosely related to someone and then snubbing/ghosting them if you're NOT invited is utterly pathetic.
Sorted the wheat from the chaf it did. Me and DH ended up with only the people who are really close and dear to us in our lives.