Do I have recourse to obtain severance

My company was recently acquired and the final closing is expected to occur in 1Q 2016. No changes are being made until closing and employees have been advised that it is business as usual relative to their current jobs. If layoffs occur at closing, severance will be paid out along with any unvested RSU grants. However, beginning this week, my department's "business as usual" has become working nonstop on gathering information and building reports and presentations needed for a series of 25 weekly transition meetings between the two sets of company execs. This is in addition to a normal workload and has now required weekends. My question is whether my employer has the right to increase my workload by 50% or greater as a result of this transition. Clearly, this is not part of the job description as it currently exists. And do I have any recourse if I decide to leave, or if I am let go as a result of choosing not to work 7 days a week. I am an exempt salaried employee.