I beleive the corpus luteum cysts is what is left after the eggs ruptures from a follicle after ovulation. It is actually what produces the progesterone that sustain the pregnancy prior to development of placenta around 10-12 weeks. This should be a good thing.
A cyst like this is common and typically takes care of itself in time and with little problem. As far as I know you don't need to abstain unless your Dr. tells you...and in my experience they will let you know. However, I am certainly not a Dr. and you should probably check with him/her. I had one early in my pregnancy and they didn't say anything about it nor seem concerned. Perhaps it depends on the size? Hope it's not causing you too much discomfort.