my boyfriend told me he cheated

he had a one night stand a few months ago. He's brought up having an open relationship a couple of times (he's pretty much hypersexual), but I've always been opposed- nothing on those who do, but it's not in me.

it was in a new conversation about this that he admitted it. it was a very even, composed discussion. I knew this relationship couldn't last, I guess, but now. just can't stop the tears.

he's being super lovey dovvy right now too, which makes it even worse.

(and of course, I just embarked on an expensive and time-consuming hobby project with him where I am reliant on his skills, help, and knowledge. so there's that)