Welcome to the forums. I'm so sorry to hear that you are hurting.
So they think the cyst is the source of your pain? I know from experience round ligament pain can be quite painful, I went to the ER vomiting from pain around 20 weeks and it turned out to be ligament pain (and I have a high tolerance for pain due to migraines). However they checked me out very carefully because that same night a pregnant lady same gestation turned up in the ER with appendicitis. I did get better with rest though.
Are you seeing a MFM? https://www.smfm.org/members/what-is-a-mfm
If not you could always ask for a referral to get a second opinion, since you are high risk due to your history and your pressures,and possible upcoming surgery. I understand your concern about blood pressure meds, my docs didn't want me on blood pressure meds until my pressures were consistently high. Also severe pain can slightly up blood pressure.
Also has anyone brought up getting a 24 hour urine test as a baseline to compare to later?