first off, im sorry you're feeling down.

emptiness and impermanence should help us to be calm, peaceful and happy -- otherwise it's kind of a malfunction.

the heart sutra says that all dharmas, all truths have the nature of emptiness, which is not created nor destroyed, not pure nor impure, not increasing nor decreasing.

that is to say, the true nature of things is unconditional. conditioned existence appears to us, but in truth it is not real, nor unreal, not both, nor neither.

it seems that you've had some good insights into the impermanence and un-satisfactoryness of conditional reality. we can say that all conditioned states are pain.

so how do we escape from this universal pain? we have to apply an antidote, which is the dharma, the union of wisdom and method.

since all things have the nature of emptiness, phenomena do not have thier own independant real self-existence. thus, nothing is inherently real in an of itself.

therefore, for an conditioned state -- say, depression in your mind -- there is always the possibility of a contradicting state to be. so we have a law of contradiction.

we also have a law of impermanence -- everything is always changing, dying away as soon as it takes birth.

therefore, we can always change things for the better in some way. we can always improve things. the dharma means there is always an antidote, no matter how dark thing seem.

in this case, the antidote is probably just to not worry about ideas. just let it go for now. maybe later on, it won't seem so bleak. just remember that your thoughts are just that -- thoughts. they only have the power yoi give them. so the best thing to do is prolly just ... relax. :)

good luck! :)