Melissa Etheridge has FINALLY settled her 2 year war with domestic partner Tammy Lynn Michaels ... TMZ has learned.

The former couple hashed out an agreement last night as part of court-ordered mediation. 

The settlement covers both partner and child support.  As TMZ first reported, Tammy had been receiving a total of $23,000 a month from Melissa, but claimed she was barely scraping by and that Melissa could afford to pay more since she was raking in $177,882 a month.

Sources connected with the couple tell TMZ ... under the terms of the settlement, Tammy will net more than the $23,000 a month, though we don't have the exact figure.

As for who gets 5-year old Johnnie Rose and Miller Steven, we're told Melissa and Tammy will share joint custody, with adjustments when Melissa goes on the road.

Lawyers for both sides could not be reached for comment.