Me and my boyfriend been together for 5 years we live together for 3 but he is married to someone else those that still make me and him common-law

HECK NO
That makes him an adulterer (CHEATER)

I don't get your answer how does that make him a cheater if he is not with her he don't know where she is all I want to know if me and him is common-law.he live with mi so he is not a cheater

Okay you didn't explain that they were not together at all so that does not make him a cheater

BUT it does not make you common law either.

A married person can not be married to another common law or marriage without first being divorced.

Very few states recognize common law anyway.

OK thank you

Uhm no. All he is right now is separated from his wife, he needs to get divorced before your considered anything but an affair.