Describing how bad our symptoms are will always sound as if we are exaggerating. People also like "bravery" from sick people so it goes against us that way too.
Now that we have so much hard evidence of what is going wrong in ME we can answer the question in a factual manner (and blind 'em with science!)
Say that the mitochondria, the batteries of our cells, are damaged so our muscles don't work, our hearts can't pump out enough blood if we try to exercise and our nervous systems and brain are screwed up.
Let's face it, we can give references to the scientific papers which describe all these things. Just because the deniers have the political upper hand does not mean we have to make life harder for ourselves by ignoring the research the way they do.
Mithriel