I have an irrational fear that my current roommate/ former friend, whom I’ve had a falling out with, might try and sue if the project I am working on gets off the ground and starts to gain traction. At no point was he involved.

That is irrational, then.

He probably doesn't have the means to sue, anyway.

Sabotage maybe, but he cannot sue when he never worked on it.

worry about taking off not about detractors....

its hard enough.

if it's out of your control, don't lose sleep on it. solve that problem when it actually occurs.

Don't worry about problems before they are..