My ex-husband and I split when my son was 3. I didn't want to stay in a miserable relationship. My son is now a happy, well-adjusted 10-year-old. While I think it's important to keep family together, children can definitely sense tension in an unhappy marriage. If you two can work together to provide two stable homes and BOTH be there for your son, working together to raise him though apart (and not pit one against the other), things should be fine. Good luck!