Do you have the transaction ID of the transaction in question?
Seems you misread the post. The OP didn't send:
I'm afraid to send this
I don't know what's wrong with Coinbase, but a zero-fee transaction might be acceptable. Sometimes, zero-fee transactions have actually been getting confirmed lately, although it may take a long time.
Worst-case scenario is that Coinbase sends a no-fee transaction and you have to use a paid accelerator like ViaBTC's additional paid service or
btc.com's accelerator. With a large amount it shouldn't be too much of a problem.
If you're really worried you can always try contacting Coinbase's support, but if this forum is anything to go by it's practically non-existent.