confused about the stage of my relationship

good day,,im cheng 28 yrs. old,,i've been through bad relationships in my life,,i separated with my husband a year ago when we had a big argument concerning about his family,i never had the chance to settle things up bcoz that time i was leaving to work abroad.we never had the chance to talk about what happen although we're notin good terms i always make it a point that i call him everyday and give whatever he needs financially.we had a child 3 of age now.last april i came back for good to work out the relationship.at first i thought everything is okay,im staying here at my parents house with our daughter.,we go out once in awhile,and twice a week he will sleep over at my parents house,everything seems to be fine until i read a msg. on his phone from a girl,i observe how often they exchange txts everyday and i found out it was his girlfriend.i write this letter to you to ask of what shall i do?? yes,i can say he still treats me the way he used to be when we're still together,he still support me in any way,,but the thing is he's committed at this girl until this moment... i love him so much,i pretend to be okay i still act as a good wife,my mind says i let go of him but my heart don't...please give me advice of what i need to do,coz im hurting very badly inside... thank's and more power...