How best can I end this?

I just found out today that my boyfriend of 6months lied to me and is actually living happily with his woman and children. Here I was all along relaxed knowing he's a single man staying with his cousin, and visits his 2 kids once in a while. This isn't the first time he's lying, there's a time he sent me dick pics from Google claiming they're his ( that was the last time we shared intimate pics) and he didn't give a clear answer as to why.

He's close to the family and since we started dating,no one from the family knows about us yet, since he's still helping my dad with some business errands.

I'm strong on my values and would never want to break a family.

What's the best way forward to end this smoothly that won't have him trying to get me back.?