Is it normal that i can't help mentioning wife's big titted friend

I can't help myself every time my wife's best friend from childhood, matron of honour in our wedding name gets mentioned I can't help mentioning, joking, or be deadly serious about her massive rack.
If she visits I can look her in the face when I speak to her. Then the minute I know I can check them without getting busted I'm fixated.
I've purposely suggested group friend trips to the beach so I can sus them, bikini, holy shit, small waist, solid around the hips trim rear and attractive although I would def score my wife higher in the all round "gets me hard as fuck" department I've found myself saying and doing some risky shit when she's around.
.i refer to her as " u know, .........'s friend ...........y with the f.........g sweet set of tits.
. My wife will say to a guest, " that's like my friend ...........y" and I instantly say " you should see the rack on her hey"
. Hate people who hug hello but she gets hello and goodbye.
. Masturbated watching her through my shed window at my wife's mothers 60 th, I snuck down the shed for a pipe green and she was busting out of a LBD.
. Told my wife during some tipsy foreplay questions and answers that I'd love to see them fuck, I'd love to fuck her tits and I fantasise about them both giving me head and my wife finishing me off by hand all over her friends custom air bags. My wife's reply was, " there not that good naked, I was going to say I want us to watch another couple that we don't know have sex, like professionals maybe" not that I would but it was a horny scenario I thought you would like" oh shit, errrrr, same here babe, I could never go through with what I said, ( pigs ass) I just thought you'd be more comfy with some you trust as a third party.
.every wank I have involves the three of us in my fantasy.
Is it the boobs, the friendship, me or a bit of all three