That's a good question that came up during a session at today's ASA meeting. Technically, the answer is yes, but the consensus is that you shouldn't do it. As a first step, one appraiser suggests that you consult with the lawyer on your side first, before leaving. Hopefully your lawyer can mandate somewhat better behavior on the other side.
But some hardened experts feel that it's OK to enforce a break, even when a question is pending (one attendee commented that as far as he knows, there is no court rule that mandates that an expert not take a break). So, whether because of a hostile lawyer, or just because you want to check your work papers rather than answering from memory, it's OK to ask for time.
A trial lawyer who is in attendance said that a good way to disarm abusive lawyers is to repeat "you don't have to raise your voice with me" again and again. If the deposition is read at trial, the lawyer will be in a difficult situation.
Another appraiser reported a situation where a lawyer accused him of taking medication for loss of memory. It takes some courage to not respond to that kind of rudeness. If nothing else, at least talk to your attorney about it at the break. The transcript is ultimately what matters--so losing your temper will only make you look equally as bad.