you just need to convert the address to a 3 address in your wallet
I can only help you with core wallet myself…
but you should be able to just convert the address using this tool:
https://litecoin-project.github.io/p2sh-convert/
and then import the address into your trezor…
your private key is alreaddy there…you just need the P2SH address in there
you dont send litecoin to bitcoins network…
all you did was send it to a litecoin “3” address…
litcoin uses “M” addresses by default but it is very easy to convert using the tool
in core wallet you would just sign the incoming transaction using your public key(addwitnessaddress)
and you would sign with the private key to send to a different pubkey/address