We had 2 children, both by C-section (emergency and planned). First one was horrible healing, very lengthy with a lot of exhaustion. Second one was easy. THEN baby #3 showed up! Also a C-section. I cried and cried about this. I wanted him, but I didn't want the C-section, I wanted to experience a normal delivery. I was very hormonal the morning of surgery and sobbing in the hospital room. Then they wheeled me into the OR, the crying stopped, I was fine. It was amazingly easy recovery too! I was happy, healthy, and healed so fast.
I know that my doc was concerned about me possibly having a 4th child due to thin uterus, adhesions, etc. They tried to talk me into getting my tubes tied, but I couldn't do that. I also found out she is a bit "c-section happy" and while I love her, I was upset in retrospect that I was whipped in for all those Cs. She doesn't like to do them past 3 children for safety reasons, possible rupture of the uterus, etc. She did tell me she had a patient who had undergone 8 c-sections, though...so you can never say never!
I wouldn't worry about a 3rd c-section being dangerous. Every pregnancy carries some degree of risk, and every delivery too...but the 3rd one is going to be fine for you!
As an aside - I also wanted #3 because I did not feel like my family was complete. My husband was ok with or without a third one. I do now feel that my family is complete, but if #4 showed up, we would also be delighted! Never say never :)