I've had 5 Ts so my answers vary. But I realize that something is wrong with me when I read that most of you are not jealous of your T's family. I have been very jealous of them (guess that's another indication of BPD).
My first T was single so I didn't have anyone to be jealous of. My second one was divorced. She did therapy in her house so once I saw her son and then I had a dream about him. My next T's husband worked with her. I don't think I was jealous of him.

The biggest problem was with my former T's family. I used to work for her husband before I started therapy and I think I liked him more than I did her. She also did therapy in her home so I'd see her adult children at times. I was very jealous of her daughter for having my T as a mother. I saw them together around my neighborhood. But I was most jealous of my Ts grandchildren when I saw her being affectionate with them once. I froze! I so much wanted to be them at that moment. I may have been out of therapy already by this time, and seeing my T only every few months.

My current T doesn't talk much about her husband, but she has talked about her kids. I'm jealous of them and her husband. When they went on a trip out of the country and I thought about them together, I had a hard time coping with my feelings. I also have a hard time when she talks about her friends, like last session when we talked about saying "I love you" to friends. She said she does, and I said I don't. So, as much as I feel secure about my T caring about me, I'm terribly jealous of her family. It's hard to read what I wrote; I sound awfully messed up.