What are the chances of me getting pregnant if I get a hysterectomy?

Zero.  A hysterectomy removes the uterus.  With no uterus there is no place for a fertilized egg to implant and grow, plus there would be no way for sperm to get up to the fallopian tubes to meet up with an egg.  As long as any future male partner is completely clean and free of STDs (and you are as well), you would never need to use condoms or any other contraceptive again.  [You say you're lesbian, but I'm including the contingent of male partner just in case you happen to be mates with a MtF trans woman who was also lesbian or bi and still had working male genitals.]

There is no way you can become pregnant if there isn't a uterus. You should know that if you have a hysterectomy, you will then need to use hormone replacement therapy to keep your bones and the rest of your body from deteriorating quicker than it would if you let nature take its course.  There are side effects to HRT that might not be so pleasant after a while.  You can develop blood clots and might be at risk for a stroke or heart attack.  It is not a "quick fix" just to avoid periods.

No way you can get pregnant if you have one. Uterus is removed. You can have tubes tied as well.

about the same as you winning the powerball lottery

Hysterectomies remove the uterus, making pregnancy impossible. Often, the ovaries are also removed, including all the glands and hormone-secreting parts, as well. You cannot have a hysterectomy to avoid getting your period, or to use as a way not to get pregnant. There are plenty of ways to eliminate the possibility of a pregnancy after rape: D&Cs (dilation and curretage), and the Day After pills that are available over the counter (i.e., Plan B).  You may not want to face this fear, but all women (and men) are susceptible to being raped in pretty  much equal numbers--most don't let it control them. And the odds are very small anyway. You've let the fear of this get out of control.

Talk to a gynecologist. No one is going to do a hysterectomy on you, but depending on your age, they may do a tubal ligation, which also makes pregnancy impossible. However, right now, you're not going to get ANY elective surgery like this, so you need to figure out a way to live with your fear and take other precautions. And there are plenty you CAN take that don't involve surgery or drastic measures. 

u will not get pregnant after a hysterectomy.

It sounds like there’s a few conversations you need to have with your doctor.

1) why you want a hysterectomy, especially if you’re still of reproductive age. Most doctors are uncomfortable performing this procedure on fertile, healthy women

2) the fundamentals of a hysterectomy. Just basic education. Because the first thing you should know is that pregnancy is not a thing without a UTERUS

Basic research would show you what that involves. As a friend of mine once said, a hysterectomy takes out the factory and puts in a playground. You cannot get pregnant without all the parts

Beware, you'll be taking hormone pills for the rest of your life

A hysterectomy removes your uterus.

You cannot get pregnant without one.

It is major surgery.

Most doctors will not consider one for a woman under 40 unless there is a serious medical issue requiring one.

Add:  there is a minimum of 6 weeks recovery time following surgery. During this time a full carton of milk is too heavy to lift. Lifting hands above shoulder height (to brush hair) is painfull.

Pretty much zero. If done by a professional, zero.