I never recommend collaborative law when one of the parties is emotionally unstable.
If both parties are OK, collaborative law works nicely in helping them find a deal with which they can both live. If one of them is a nutter, then the odds are that at some point in the negotiations the nutter hold his or her breath, stamp his or her little hooves, and sabotage the process. The lawyers will do their best to keep the matter on track, which will add to the tab due to the extra time put into the matter. Then when it becomes obvious that the nutter will not be satisfied, both lawyers will quit (that is part of the collaborative law contract – the part that is different from the regular negotiation/litigation process), leaving the parties having to hire new lawers and get them up to speed on everyting so that the matter can go before a judge.
If one of the parties is a nutter, I recommend that the parties find lawyers who have their collaborative law tickets, but then hire them for the regular process (negotiation and if necessary litigation), rather than hire them for the collaborative law process (negotiation or else quit).