You are just learning that in areas of relationships, what people say and what they actually want can often be two different things.
“I told them that their ex had asked me, and they seemed excited and supportive.” Yes, because they care for you. But because you care for them, you need to be absolutely sure they feel this way before you accept. Have private conversations after they have time to absorb the information.
So maybe you were TA, but just see it as a learning experience and apologize.