My divorce was final almost three years ago, but there's never been a distribution of assets and liabilities.
Why not? Does your divorce decree say anything about the division of marital property? If not, why not?
I assumed responsibility of our martial rental properties and my ex took control of our retail business.
Did this just happen, or was it pursuant to the terms of the decree or some formal agreement?
Am I able to take funds from the retail business account to pay towards these properties?
We have no way of knowing what you're able to do. You didn't tell us if this is an account in your and your ex's names or a corporate account or an LLC account. You didn't tell us if you're a signatory on the account. Etc., etc.
I suggest you call the lawyer who represented you in the divorce to discuss this. If you didn't have an attorney, you now know why you should have had one and should get one ASAP.