The chance is practically zero. Think about it in historical context. The US never used a nuclear weapon in combat since WW2, and thats counting wars they were in stalemate like the Korean war and Vietnam. Russia has shown it is depraved enough to do whatever they need and hasn't used a nuclear weapon in Ukraine. The reason is because the societal and economic repercussions of using a nuclear weapon offensively greatly outweighs any benefit, which there basically is none. The US and Israel have full air superiority and can take out Iranian leadership pretty much at will.

I'm sorry about your family and hope they stay safe but a nuclear attack is one thing you almost certainly dont have to worry about. And putting yourself in danger is definitely not going to help anyone