Hi D.,
Your feelings are actually quite common. Life has many changes, it is not unusual that you have changed as well. Currently you have had a major shift in the focus of your life.
With two new babies it is inevitable that your relationship will change. Please do not do anything drastic about your relationship right now while your life is in such transition.
Men also feel the change in the relationship which comes with parenthood. Often they respond differently. While you are occupied with the day to day care of two very dependent human beings, men often withdraw, realizing it is selfish to complain about your new interests (which of course are his children whom he loves dearly).
The family is a precious unit greater than any of the individual members. It is important to preserve your family if at all possible. If your husband is essentially a good man, please try professional counseling by a counselor who believes in the value of family. (not all do) before making any drastic changes.
Though it is hard to imagine it now, your little ones will grow up and your husband and yourself will grow close again. Often people bail out of relationships because they are "bored" or somehow not satisfied, only to repeat the same relationship over and over simply because their expectations are unrealistic.
No one human can give your life complete meaning and purpose. It is the slow, steady committment of marriage that increases security and feelings of trust and intimacy that leads to a strong, healthy marriage. A true marriage will be there through all the phases of your life with the understanding that the marriage will have a natural course of times of greater and lesser intimacy.
Best Wishes and God Bless.
J. L.