How do i trust my husband now?

im married for 10 years.a good husband.a son of 8 years.he loves us but never spends time for the family.for the past 1 year his attitudes started changing.he became aloof from the family.he used to help his sibling emotionally and financially.now he quarrels with all of them saying they are only after money.he never told his hi financial position to me,but i know he is in deep trouble financially.he used to tell me that his secretary knows all about his dealing in business,little did i know that he used to discuss even personal matters with her (she told me ),when i confronted him,he agreed without a bit of guilt..she married a year ago , he not only financed the marriage but personally shopped with her ,took her to beauty pa lours and spent hours with her on the pretest of discussing about the marriage.i openly told him what he was doing was wrong.he doesn't seem to care about it.she also knows but she doesn't care too.hes told her that i don't take care of him which is false and he knows it too. why is he creating self pity .she texts him every time and talk for hours together in the night.her husband objected to it.so they do the talking in the office.once he even told me they share a similar wave length and she was his let out .she controlls him so well that he cannot come out of her clutches.i don't trust him any more.he is so depressed now that now he locks himself in his room after he comes home and watches tv .he doesnt talk to any one in the family.im scared i want my husband back.