Supporting my partner through therapy?

How to support my (19f) boyfriend (28m) through therapy?

So Friday I ended up telling my boyfriend something his mother had said about him, that was rude and uncalled for. He was deeply hurt by her words and eventually called her to let her know how upset he was for her words,

Eventually things from his past with his mom got brought up and it sent him into a breakdown where he decided to get therapy. I fully support and encourage him to get therapy, especially after hearing some of the things that he has gone through with his mother.

So how do I best support him while he starts his journey with therapy?

Also, I know this may not seem like a very large age gap to some, but when posted in an advice sub, there was nothing but hate for the difference in our ages