Help..friend gets very upset if i mention i want to date a male?

I'm a 42yr old female. I just landed a great guy, 53 and a surgeon. Well at least i think i've landed him. I met him in a bar, drunk off my rocker and we had a good time in the bedroom...twice. I'm a bit of a looker, i take good care of myself. The problem is my friend Kat. Kat and I share a house for over 20yrs. We do everything together.Heck, there was a time when we even had the same boyfriend (after one of us dumped him). She is very clingy toward me. Heck we even cuddle up if the night is cold (not in a ual way, we both raging hetros here). We go out 3 times a week, we pull and we screw, but the rule is we dont get involved. Anyhow most of the geezers are loosers. However, this guys got a lot going for him n i think i want to make a go of it with him. I want to chase him down good and maybe secure a future with this guy...babies, our house, a family. But Kat....she seems so upset. Hes been round to this gaff once...and she was dead cold toward him, insisting 'our rule' is we dont bring the geezer to our home. However thats 'her' rule, not 'mine' and its 'my' home too. I put up the money (with help from my old man) for half the rent n bills. I want a family n kids, the whole works. But i dont wanta loose Kat. Anyway, my new mans gone cool on me, hes been blowing hot n cold this past 3 days, the texting has stopped. I went for a meal with him, but he wanted to skip the eating part and go upstaris to a room in a fancy hotel. I put my foot down, i aint goin to be treated like no tramp. I told him conversation is whats on the menu from now on, and 'developing our relationship'. I feel used, maybe Kat is right. Kat sits around all day smokin n drinkin beer. I decided i dont wanta life like that, i want a job, and another life. How do i keep my friend n snare my man. Right now my life with Kat entails getting up late, sitting brooding with 20 fags and strong coffee well into the afternoon. Then we get all done up, hit the mall, buy come clothes, throw on teh slap n hit the early bars, rolling in late at 5am. I feel too old.