You've gone through a lot in this relationship in a short amount of time. It is a lot to process. Going no contact would definately give you the space you need.
In answer to your questions, here is my honest feedback (please take it for what it is worth)...
Should you talk to him about going no contact?
You can let him know you are going to do this (I would given you were once engaged) but he won't be pleased. Are you prepared for that reaction? Are you strong enough to withstand the emotional stuff that he may stir up with the conversation? If it is going to make matters worse right now then I'd think about whether telling him is good or counter productive.
Should you go no contact?
If it is for the right reasons then yes.
Will going no contact help?
Help with.... what? Be clear with yourself what the goal is because sometimes no contact can be more of a manipulation tactic then a boundary. You may break it and feel bad and then this other cycle begins for you. I guess my only concern is it would be difficult to go no contact if you still interact with his family. It may take distancing yourself from them if you want to clear yourself of this.
I think you should go no contact, I don't know if you are prepared for it though -- you are still attached and worried about him. If you can truly detach then you'll benefit from no contact.