I'm having trouble understanding exactly what this person is saying to me. The context being that I was asked a question by them, and after responding they said this:
そうでしたか！それを聞けて逆に安心しました…！笑
I believe: そうでしたか！ = Was that so!? And maybe: それを聞けて = Able to hear that and ...
But: 逆に安心しました = was oppositely relieved (?) Does this mean they became relieved, and were worried before (the opposite of relieved), or something else?
It means "(I probably shouldn't have heard that) but when I could hear that, I was rather relieved ."
逆に in this sentence means "on the contrary", "rather". For example, 失敗して逆に良かった(I failed, but on the contrary it was good).
It means the feeling of being relieved goes against what one might have expected, perhaps contrary to what the person themselves expected.
So that's how it was? Despite what [you/I] might've thought, I am relieved having been able to hear this explanation.
What exactly that expectation that was broken is depends on the context and cannot be inferred with certainty here. One guess, which makes this sentence less convoluted sounding:
So that's how it was? I was afraid to ask, but hearing this explanation I'm glad I did.
Or perhaps:
… Despite what you might think, I'm relieved you explained it to me.
(This would be the appropriate interpretation if your explanation might put the person into an awkward position.)
It's also possible that it doesn't have any particular meaning at all and is mostly a habit of the speaker.
