You have to use hot towel to massage on the breast and then let bb suck the milk to empty the breast! It's painful when you massage it, but once the milk duct is being cleared, you will feel better.
In case you want to stop bf (which is a great pity), I heard that you can go to chinese medicine shop to buy some 收奶茶 (i've never tried it though), it helps you stop producing milk, however, my friend told me that it may make your breast shrunk quickly and soft suddenly... so... it's better to let it stop naturally, I think.