Deciding about whether you should get a divorce or not is an agonizing experience to go through. If you are asking yourself "should I get a divorce?", you've been thinking about your relationship's state for a while or an isolated incident (an example is an extramarital affair) that occurred was so terrible, that you want to just chuck it all and start over with a new life!
If you have been asking yourself "should I get a divorce?" for any length of time, you should figure out what is making you feel that way if you haven't already. Take time to reflect back on why you're leaning towards divorce rather than working out your marriage problem. Once you identify things that are making you feel like divorce is right option, make a list of those things.
Once you make that list, go back through each item on list that led you to asking yourself question "should I get a divorce?". Look at each item on list in depth and make certain you really deem those items as valid reasons for wanting a divorce, either in and of themselves or as a part of a common theme of reasons that make up a whole set.
Once you trim list down to include only truly 'valid reasons', rank each reason in order of importance. Identify 2 reasons that hold most weight to you and that contributed most to you asking yourself "should I get a divorce?".
After you accomplish this, decide if these reasons seem like things that can be changed for better or if they are just flat out unrecoverable. Soul search and decide whether or not you are willing to do what it takes to try and fix problem that is associated with these reasons.
Example: If one of your reasons for thinking about divorce is because your spouse is insanely jealous of you having friendly and/or purely plutonic relationships with members of opposite sex, decide whether or not you are willing to socialize less with members of opposite sex (or in a different manner) or do what it takes to ensure that your spouse understands and believes that you truly love him/her. If you aren't willing to do either of those things (or anything else it may take to change situation), you have some serious long-term thinking to do about whether you really want to stay married.