When a distrusting telepath learns his whole life has been a lie, he must take on the shadowy agency he works for to uncover his real past.

"While struggling with an identity crisis": I think this is implied by the fact that he discover that his life is a lie so it's not useful in the logline. And despondent is not a good characterisation for a MC in my opinion.

"When a skilled telepath discovers his whole life has been a lie, he must take on the shadowy agency he works for to uncover his real past."
You have an incident (he discover his life is a lie) and the goal (uncover his real past).

You could also find a way to avoid the couple discover/uncover, that sounds poor.

I guess looking for a way of saying he is suffering from an identity crisis about the type of person he wants to be and discovers that his past, the foundation of who he is false

Cheers for the feedback. Yep, the excitement I get when I think about where I can take this story makes me want to write it. But I have to start from a solid foundation, which means nailing a logline which I am trying to do. And thanks for all the feedback I should be able to do that.