Normally the value of the survivor's pension of your ex would not be included in your assets.
However, if you already have an irrevocable entitlement to the survivor's pension, then it would be included in your assets. This could happen if separation occurs after the pension payments have started. That is basically if you were still married when your ex retired, you'd have an entitled to the survivor's pension. A divorce later on wouldn't end the entitlement.
I don't know enough about your case to say for sure, but you mention that this is your ex's former workplace. It sounds like his pension may already being paying out, in which case you probably are entitled to the survivor's pension.
You may never get the survivor's pension, but that probability is calculated by the actuary. The actuary calculated your and your ex's life expectancy based on your current age and life expectancy tables. The one thing that may change this is if you currently have a bad health condition.
Your ex may also pass away tomorrow and you'd end up with significantly more survivor's benefits than calculated by the actuary. It's somewhat of a statistical calculation.
In any event, you should get your own actuary to double check the calculation performed. I wouldn't just rely on the information provided by your ex's actuary.
