This is really scay, and I hope that this is nothing to worry about, and that you'll be inconvenienced, nothing more.
Having said that, my mom had an ultrasound-guided biopsy that was very painful, and bruised her extremely badly. It was shocking, and it was bad enough that I wish they would have put her under general anesthesia for the procedure. Find out from your doctor and see what your particular biopsy is going to be like, and if anesthesia is an option for you.
Having said that, it's VERY IMPORTANT for you to focus only on the information you know when you know it, and the options that are presented to you. Try not to dwell on the "what ifs" until you know more information. Right now, you know you have a "lump". That could be a lot of things, with a wide variety of treatment options. You don't have any more information, so go through all of the recommended diagnosis tools until you have a confirmed diagnosis and a recommended treatment plan. Then, do your research to find out how your particular diagnosis and treatment plan will affect you. Ask a LOT of questions of your doctors when they meet with you. Get an understanding of how your particular diagnosis works, how they came to the diagnosis, how it is differentiated from other cancers, what the treatment plan is (start to finish, duration, etc.), what the side effects are. Find out if you can reach out to support groups of people with the same diagnosis as you.
My Mom was diagnosed with Stage IV breast cancer earlier this year. The worst part of the diagnosis process was how long it took to get all of her tests done to understand what type of cancer it was, how far it had spread, and what the impact of her treatment plan would be. The whole process took about 3 weeks to go from the possibility of a very, very bad disease(multiple myeloma) to her actual diagnosis. My Mom's prognosis is very optimistic with her current treatment plan. She'll have this disease for the rest of her life, but the treatment has not impacted her quality of life, and there are others who have been in this treatment for 15 years.
I hope this helps. I'm praying for you, and hoping everything turns out just fine!