There is no good answer for this. Saying no, is just, saying no. Anything less is beating around the bush and avoiding the issue. Be firm in what you want and/or don't want to have happen with relationships and people. take care of you first, there will be some people that are hurt by it and others that understand, you have no control over this fact. I would venture to guess the mature ones that are worth keeping around as friends will be the ones that understand and the ones that take it personally and are offended are probably never going to be the type of person worth trying to keep a healthy relationship with.