Let me get this straight...I'm a little confused by your post.

1. Dad broke up with step-mom.
2. Shae is a female NOT a male
3.Shae is living with Dad.
4. You're living with Mom.
5. Step-brother is now out of the picture.
6. Step-mom was NOT in the room when it was happening, but could hear it.

How was that??? How far off am I?