just found out partner is a sex addict

There may (or may not) be more remorse there than you see.  We end up trapped in our addictive behavior, wanting to stop, unable to stop, too shamed to confess, desperate to make it go away and stop the lies, but unable to make that happen.  Not every addict realizes that what they are doing is wrong, but for those who do, it's hell.  I spent 30 years knowing how much I was hurting my wife, trying to stop, and failing.

Of course, we also hide that pain from ourselves by learning not to think and not to feel.  Part of recovery is learning to feel.

Whether or not this gives you insight and empathy for the inner experience of he addict, do make sure you are getting the care you need for yourself and for your child.  You obviously need a full suite of tests for STDs, and you need to continue to do whatever it takes to be safe.  We often lie very convincingly.  Be careful.  Make sure you are getting both medical and psychological support for yourself.

It's good you've found places like this, and, of course, tragic that you needed to.

Tim M.