bent grass

large patches of my front lawn die off each fall and I am told it is bent grass. I pulled out some patches of it by hand and sprayed weed-b-gone on the larger patches of it towards the end of the fall (early November - I live in Connecticut) and put down new seed, some seedlings started to grow but i think it was too late in the season. Now that spring is starting and snow has melted most of my lawn is brown/yellow dead "grass". Should I pull up the "dead" bent grass and plant new seed ( more than 50% of my front lawn), even though fall is the best time to seed? If yes, I do get crabgrass every year so wanted to put down a crab grass preventer in early spring, so in what order should I seed / crab grass prevent. Is here anything that will get rid of or prevent bent grass?
thanks.
Karen