Charlie Sheen Smokes Peace Pipe with Brooke Mueller

3/17/2014 12:40 AM PDT

Charlie Sheen Smokes Peace Pipe With Brooke Mueller

There's nothing like a common enemy to unite enemies .... just ask Charlie Sheen and Brooke Mueller

The ex spouses -- who have been at war for months, with hideous superlatives thrown back and forth -- are "friends again" ... thanks to newly-minted arch villain Denise Richards.

Charlie and Brooke hosted a party for Bob and Max Saturday, and by all appearances got along great.

Charlie Sheen threw the shindig at his house for their twins' 5th birthday ... and planned it with Brooke and fiancee Brett Rossi -- it was very wholesome ... bounce house and all.

As you may recall ... Sheen and Mueller have been in a legal tug of war royale over custody ... Charlie accusing Brooke of screwing up the kids by doing drugs while she was pregnant.

Charlie is on a tear now against Denise because he feels she's not giving him enough access to their girls.  Brooke hates Denise ... possibly because she's threatened that Denise has been the go-to mother when Brooke went in and out of rehab.

One big happy family.