Dear Abby: Half-sister obsesses over newfound brother

RO-51

DEAR ABBY: Six months ago, my husband, "Lee," met his long-lost sister, his father's daughter from a previous marriage. Lee's father passed away when he was 6; he is now 30.

Since he and his four siblings met their half-sister, she has become obsessive over him. She calls and keeps him on the phone for hours, three or four times a week. I didn't mind at first, but it has gotten out of control, and she constantly texts him.

If Lee doesn't respond, she texts him asking if he's angry. She expresses how "in love" she is with him and how happy she is to have met him. (She doesn't say these things to the others.) When I recently expressed my concern, he got offended.

How should I cope with this? She also says unflattering things about me to him and tries to turn him against me.