the environment in a downsizing company is very toxic

I'd been in the same situation.  I hated walking into the building every day.  The best option is to find a job in a company which is either stable or growing.  The fear of layoff really makes people act selfish, and as a result, more politics.  If you have to stay, just treat a job as a job and do not take it too personal.  Make sure that you get the credits you deserve, not being negative in a group setting and in front of your boss, work 8-5 and spend the remaining time with your family.  Develope solid friendship with few trustworthy coworkers so you can vent out your feelings.
Wish you best luck!