well first off, I learned in my abnormal psych class, the knife thought is a perfectly normal thought. he gave that exact example as an example.

as for the rest of it, make your boundaries clear. you work from home so you need to put time aside to do that.

and then try to remember that they aren't bad people. you may not be affectionate with them, but try to bring up any positive feelings you have toward them when you are around them, remembering fondly the good things they have done for you and hold on to these positive thoughts and it will be easier to be around them.