Hi
jessiejaker;
you may want to deal/confront the situation before he arrives Canada. Remember, once he is in Canada you are financially responsible for him for 3 years (and he is not eligible for financial assistance during this period). You may want to review the contract you signed again to understand what you are on the hook for once he arrives. If you decide to withdraw your sponsorship before he arrives - he will not be able to enter Canada.
I suggest you speak to an immigration and/or divorce lawyer and get some legal advice.
All the best,
If the marriage is falling apart, it is time to withdraw the sponsorship before he get here.
PMM
T