Brooklyn says she’s been dating Eric, a married father of two, for at least 10 months. She says their relationship is sexual, and it’s “perfect,” and she says she believes Eric will eventually leave his wife, Mandy.

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On Monday’s episode of Dr. Phil, the 18-year-old faces off with Mandy, who says she’s ready to fight for her marriage. When Brooklyn claims to Mandy that she’s not the first affair Eric has had, Dr. Phil steps in.
 
“Do you realize how much that cheapens your relationship with him?” Dr. Phil asks Brooklyn. “There’s an old saying, ‘If they’ll do it with you; they’ll do it to you.’”

WATCH: Woman Comes Face To Face With Husband’s Teen Mistress
 

See Brooklyn’s response in the video above – and hear what else Dr. Phil has to say to her.
 
On Monday, will Mandy decide her marriage is still worth fighting for? And, will Brooklyn acknowledge that Eric could be lying to her? Check here to see where you can watch.