How do you bring up having std in a previous relationship?

I was in a long term relationship and he gave me herpes. I guess he didn’t know he had it too. We broke up but now I’m seeing a new guy and I don’t know how to bring this up to him. I feel so embarrassed. I didn’t have multiple previous partners. It was just my ex. I really worry about what the new guy will think of me.
How do you bring up having std in a previous relationship?
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