Taking a Break - help!

Husband (42m) and I (39f) are sitting down tomorrow to discuss taking a break. I don't know what that means (to him). We've been in therapy together, but our marriage is failing.

Any tips and insights for our conversation tomorrow? I don't even know where to begin. His idea is that he'll move his things downstairs but we have a toddler and we'll both be in the house. What points should we touch on? I don't even know if "break" and "separation" are the same things?

Wondering what other people have done in similar situations, and if the break helped the relationship succeed, or was it just the beginning of the end?