As everyone says on here, believe nothing they say and half of what they do.
If ex husband #1 is the father of SS22, then she may be telling XH#1 that SS22 has his own room because she wants him to think he's okay.
I certainly can understand the pain and urge to react, but I would caution you to take it a little slower to further confirm what's really going on.
Me: 43 W: 37 Together: 18 M: 15 D: 8 yrs old ILYBNILWY: March 2011 She Filed for D: August 2011 She moved out: Sept 1, 2011 Reconciled: May 2012 Divorce Case dropped: July 2012