Export the private key corresponding to the funded address from your BTC-electrum
import this private key into a bitcoin cash wallet (depening on the wallet, a rescan might be needed)
Mark the BTC address in electrum as compromised, never use it again. It might even be wise to empty the BTC-electrum wallet and stop using it.
EDIT: i forgot: before exporting the private key for the deposit address from electrum, make sure there are no unspent outputs on the bitcoin network funding this address... If there are, it might be wise to spend these outputs on the bitcoin network before exporting the private key from electrum and importing it in an bitcoincash wallet... Bitcoincash wallets seem to be pretty secure, so the chance of them exposing the private keey are minimal, but it's better to be safe than sorry!
let me see that I understand :
1. In Electrum wallet : Wallet ->Private keys - > export
2. save the exported file on my desktop.
3. download a different wallet (BTC.com ? BU Bitcoin Cash Client?)?
4. import the whole keys to the new wallet ?
5. In Electrum wallet : Addresses->Right click -> Freeze
Am I right ? Am I missing something ?
Thank you !!!
Allmost
1: in electrum wallet -> view -> show coins
2: open coins tab
3: check if deposit address has unspent outputs (coins)
4: if true, ctrl-click on the unspent outputs, select them all -> right click -> spend (fund an address generated by a new, clean, encrypted wallet). If false skip to step 6
5: wait untill tx from step 4 is confirmed
6: In Electrum wallet : Wallet ->Private keys - > export
7: save the exported file on my desktop.
8: locate the private key belonging to the address you wrongfully funded on the Bitcoincash network, copy this private key
9: download a Bitcoincash wallet, for example electroncash (but other wallets work as well)
10: open electroncash, generate a new wallet using a PRIVATE KEY (not a seed)
11: paste the private key from step 8 in the wizard's interface in due time
12: spend the output on the bitcoincash network
13: clean up everything (as soon as the tx from step 12 is confirmed, delete the electroncash wallet, delete the file from step 7,...)
14: In Electrum wallet : Addresses->Right click -> Freeze
14b: even better, create a new wallet, generate a new deposit address, go to the old wallet, click on send, paste the new deposit wallet and click on "max" (empty out the old wallet). Don't use the compromised wallet again (if possible). This last step is an alternative for step 14 in case you're a paranoid person (like me)