This is not the first time your wife has played this way. She has a routine. She blows you off while your two friends take turns penetrating her. She doesn't like condoms and at her age, she can't get pregnant. So taking creampies is expected. You were so proud of her as you watched her taking one white cock after another. She wanted to show you what your two friends left her. And yes, as the husband you are expected to put the last load in her.