My story seems to be stuck.

If you know my story, then you probably know. I left a massive cliffhanger in my prvious chapter where my main character finds out that he is a descendant of a t royal family that were all executed. It could all be a joke, but its not. that he is a descendant of the Romanovs. I have some ideas where to go but how to proceed and connect the story to where I want it all to go.
First, I need to decide how to get out some important information on how this all occurred. I have an idea of an old box, some heirlooms and handwritten letters from the survivors like his mother and the original escapees and how it all occurred. But, its a lot of seemingly useless exposition and handwritten letters that may bog it all down. Its all important to the story, or will be when its all connected and put into action. But how do I do all of that
What can I do