I may not be the best person to follow up about this… others on the forum are more current on advising people about using the wallets and investigating losses… but you may be facing an emergency so I wanted to send this to you ASAP.
Your delegation to the MELD pools and your apparent loss of all your funds (or maybe just a wallet sync problem) are 2 separate events that cannot be related. Your delegation to any pool itself is a secure transaction that would never give away your private key, which would allow that pool to transfer funds out of your wallet: therefore something else must have happened.
The cost of 99% for the MELD pools isn’t the cost of your delegated ADA… it’s the cost taken out of the rewards that you receive. MELD keeps almost all that ADA and gives you MELD instead when the ISPO is over… not for about 2 more months. In the meantime you have to find out why your wallet balance is showing zero.