Surely your 10-year-old knows that the reason her mom sleeps with her and her siblings is due to your marital problems. My guess is that the 5-year-old has come to some understanding of this, as well. You and your wife are upsetting your kids and scaring them as a result of your unhealthy relationship with one another. Please see a therapist with your wife to help you both deal with your marriage and stop involving your kids indirectly in these problems. They deserve better.