There are two levels to consider. First, and I mean no disrespect, your idea is not unique. It's not worth anything on its own, without execution. Other people

There are two levels to consider. First, and I mean no disrespect, your idea is not unique. It's not worth anything on its own, without execution. Other people probably had, have, and will have the very same idea. The only special thing about it could be the timing. So if you think the timing is right, the idea is good, and you can execute well: by all means go and do it! Secondly, yes, there will be backlash. People will accuse you of things. You say it was your idea, but you'll be surprised how selective everybody's perception is. To minimize both fuzz and sabotage, you need to make a clean cut. It needs to be a surprise, and there must not be any transition period. Whatever code and other stuff you created at your old company, do not take it with you. Do not tell anyone details about your plans. If you shared financial commitments, you should compensate those people now, before they have a chance to complain. Do a clean shutdown. Be guarded but truthful.