The singer and 'Real Housewives of Beverly Hills' star filed divorce docs in Los Angeles County this week -- seeking a dissolution of marriage from her powerhouse attorney hubby -- who's more than 30 years her senior.

It's unclear what she's seeking at this point in terms spousal support -- if anything at all -- but we're working on getting more info. It's pretty shocking news considering they've been together for so long now ... the two got hitched in 1999. Last millennium, folks!

They share no children, but probably have a ton of assets between the both of them after all these years -- they're incredibly wealthy.

Erika became a regular 'RHOBH' cast member starting in season 6, and Tom's made several appearances as well.