The warning signs are consistent and worth taking seriously: chasing losses, gambling with money set aside for something else, hiding how much you play, borrowing to play, and needing to keep going in order to get even.
Help in Canada is free and confidential. ConnexOntario answers 24 hours on 1-866-531-2600. Every province runs an equivalent service, and the Canada Safety Council publishes a national directory of them.
This is the most important thing on this page. Provincial self-exclusion schemes, including the one that covers Ontario's regulated market, bind the operators licensed within that province. Every operator listed on this site is outside those schemes. An exclusion you registered with a provincial operator will not stop you opening an account here.
If you have self-excluded, the tools that do reach offshore sites are blocking software installed on your own devices, and a bank gambling block, which most Canadian banks and several app-based accounts now offer and which refuses gambling merchant codes at source.
Combining the two is far more effective than either alone, because one closes the website and the other closes the payment.