If the support is only for spousal support (not child support) and pursuant to a court order or written agreement, the full amount will be taxable to your former spouse and a deduction for you.

If a lump sum has been paid, the rules are somewhat different. Here's a link for more information: https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-re...