Mel's Rumored Russian -- All Knocked Up!

4/15/2009 12:39 PM PDT BY TMZ STAFF
...by her own husband.

Oksana Kolesnikova: Click to watch
Both Mel Gibson and Russian singer Oksana Kolesnikova have already blasted affair rumors -- yesterday in L.A., a very upset Oksana insisted she's "happily married" -- and 4-months pregnant with her hubby's child.

Mazel tov!