Do u pity Charlie(bella's father)since he is always kept in the dark:that he doesn't even know what Bella is upto?do u think it is a blessing in disguise?

I think it is somewhat of a blessing because Charlie would be so much madami upset if he truly knew what was going on. Not to mention he would try to keep Bella away from Edward even madami which could put a strain on Charlie and Bella's daddy daughter relationship. I don't necessarily think Charlie would have wanted to know anyway, especially after how in Breaking Dawn he says he wants to know basically as little as possible. So I think that it is somewhat of a blessing. :)

i think it is a blessing for both bella as well as charlie cos then they both aren't worried

Yes, because any human knowing means that the Volturi will either kill that person or force him to be turned. Also, in Breaking Dawn Charlie basically reveals that he wants to know as little as possible. The whole supernatural world seems to be too much for him.