Your wallet is probably under attack and you should be moving your fund's out of that Wallet already, because it highly likely that that wallet have been compromised based on what you explained here so for sure the sender spam your wallet just to test his access to that Wallet and you being a victim thinks he is doing you a favour, probably he be monitoring the wallet by now and if youake any large deposits in that wallet then you see the scammers hackers in action.
Lastly for the sake of clarity, do you say you are holding the coin on your coinbase wallet or on you normal ether wallet, because the whole thing sound confusing at this point.