Can I have Jello Sugar Free, Pudding?

I read this great post somewhere... you can add a pinch of sf jello any flavor to enhance the flavor of the pudding (especially the vanilla and cheesecake varieties.  Like, cherry or strawberry in the cheesecake flavor.  I just bought a ton of all to try it.

I tried to eat it, but it caused me horrible gastric distress.  I can eat the type that you make yourself, if I make it with lactose free milk, but the individual cups make me very sick.