You have had alot of surgeries, and your Dr has said that it seems to be attached to the bladder, I would go to a Gyn/Oncologist. You have scar tissue inside that makes the surgery more complicated and I would want the surgeon who does the most complicated surgeries operating on me. They have 3 additional years in women's surgery, no babies delivered and not the usually hysterectomies. Go for a second opinion and consider having them perform the surgery. Given your previous C sections, I believe that they would do a laparatomy again. Good luck to you, sounds like you have a busy Holiday with you children.
Gosh you've been through quite a bit with 4 c sections and a laparoscopy too. I had a tubal ligaton 8 years ago laparoscopically and two weeks ago had a laparotomy for a 8.5cm cyst that had grown from 5cm in several months. I was shocked when the specialist told me I would need the laparatomy for the cyst. I had gone to my appointment thinking that if I needed to have it out it would be relatively simple and would be done laparscopically. He told me the cyst was too big and it was much easier to remove without complications this way. A frozen section was performed at the time of the op and everything was OK. After the operation I was told that the cyst was growing around the ovary and it would have been impossible to remove without the ovary as well. So my guess is you won't know until they get in there what might happen. The added complication of your ovary being attached to the bladder sounds like a difficult situation for you.
As for laparscopy vs laparotomy - laparscopy is relatively simple in comparison, although I was pretty sore afterwards for a few days but at least you can go home the same day. You will know what a laparatomy is like having had 4 caesars! Much longer recovery period, that's for sure.
It's not pleasant having a cyst rupture - that's what happened to me, but even after that they monitored it for several months before doing a repeat scan. I had extreme pain and vomiting after falling down our steps one day. The cyst was finally discovered but the pain settled down and because it was just before a weekend and our hospitals were very overful at the time, it was decided to see what happened, and if it got any worse I would have to go to hospital. It gradually improved so nothing was done for several months. Although I did a bit of reading about cysts I did trust my doctor and perhaps if I'd discovered this forum back then I might have panicked. It was really only the 4 weeks from the time I visited my specialist to the operation that I was worried about cancer. I would be interested to hear how you get on, keep us posted. Take care.