Relationship. thoughts, opinion, and advice....?

Me and my fiance have two children together we broke up after our first child for a year we got back together he finds out he has another kid two months after we break up. while we were broken up we talked everyday but were not together... During the time we weren't together he never mentionedThis situation to me.he tells me about his other kid after we got back togetherand when her gets dna test results... He said he didn't say anything because he wanted to make sure the kid was his and. I've knwn his kid for a little over a year now decent kid clings and is only comfortable with only me. but I'm still very very hurt by the situation also because throughout our breakup he was hiding that from me. He's a really good dad and provider this has changed or relationship I'm not sure if I still wan't to marry him or even be with him.