App Crashing/ Corrupted World

I have an issue that I have tried searching for sometime. I have seen several videos and articles that are meant to address the issue but none of them work. 
My issue is that my longtime survival world crashes the game when it tries to load. I can play other worlds but every time k start this one which is very important to me it crashes. I also have occasional “updating pack” and that can range from once to multiple glitchy flashing screens only to then go through the load as normal and immediately crash. The world is also  20mb larger than it has been every other save. Can you help me? Please.