I understand what you must be going through. You had patience to be with her for all these years despite too less sex and even after being unsatisfied sexually with her. Even though its common for women sex drive to reduce little bit after having baby but major reduction in sex is found after only 40-45 years for female. I dont understand why she is having pain in sex even after baby. Is your dick exceptionally larger or her vagina is too small? or may be she lacks sexual interest which make sex in-comfortable to her. I think your wife is having some harmonal problems. Kindly visit a Harmon therapy doctor who can check if her estrogen levels are below normal and suggest why is she having this problem. He can also advice some medicines and guide you both to have better sex.