coming out soon, need help!!

Hey everybody, I'm new to reddit although I've been a lurker for a while, and like the title says I need some guidance coming out to my friends and loved ones. I will be very appreciative of any positive or honest feedback! I'm 38 and I am gay. I have been into guys for a long time, since 13 or 14, my first sexual experience was with a man, but I suppressed my wants and feelings ever since due to personal and social pressures. I've had many gf's, I have two daughters and I currently have a gf who I live with. The last year to year and a half things have changed in that I have realized and accepted that I am gay, instead of at first telling myself I was just in a phase (for 25 yrs. lol), and that I'm just bi. I have zero attraction to my gf, and women in general. The prospect of actually going through with this is really freaking me out, and I would really like some input on how to handle it. I'm really a pretty private person and consider it my business, but I know it will eventually be known anyway... I'm most unsure of how to handle my gf :( Thanks in advance!