What should I really do?

me and my wife have been together for two years now. at first our relationship bloomed like crazy we fell in love so deeply, it was awesome..when we met she was going through some stuff but i helped her and stood by her side no matter what, months ped by and we just fell more in love everyday. she stopped talkin to her ex's and i didn't talk to mine cause i see doing that as wrong. well months ped by and it was great, then it started to get to where we kinda started having problems, but thats every relationship. we had our little arguments, and together we got through them the first year was awesome.a after a while we fought more,but we'd get over it, sometimes sucked, some were beautiful, we now have a 5 month old baby that i loveeee so much she is my world. we have vbeen together for 2 years now. but in december this guy started to txt her..at first she ignored him..but after a while she started to txt him..she told me he'd txtd her and i told her i didn't want her txtn him..we'd get mad but fix things and she'd not txt him any more but it was only a matter of time before it started again..lately for like the past month or two me and my wifes relationship has been so good, we don't fight really.when we get upset we realize that we love each other and just fix tings together.its awesome.tings could'nt be going better. yesterday i worked with my wife cause we work in the same place, different departments so its pretty good. yesterday we worked together and she came to see me before she went home. it was awesome we hugged and kissed, it was such a good feelling, t when she got e about after an hour she txtd me tellin me she had to talk to me..so i was like about what??..she was kinda difficult about tellin me,,..but then she told me i've been talking to a guy..so i asked if she was talkin to him like "that" or just as a friend.. she told me sort of in the middle.. so i was like what??? :( she told me she was like talkin to him like that so i stopped talkin to her until i got home.. then i called..at first she didn't answer but after a lil she answered and we talked.. i didnt lash out at her screaming and acting childish..i just asked her who it was..she didn't answer.. so i asked if it was a guy from school..she said it wasnt then i asked if it was that guy..so she said yes..i asked if its an everyday thing that they txt..she said yes but that it hasn't been long..and well that they hadn't talked on the phone..i don't think they've seen eachother..the last time was probably before we started dating...i asked her if she likes him but she doesn't answer..i think she likes him and wants to be with this guy.... my thoughts are getting tered now, .. i try to be the best guy to her..i don't cheat on her.. i do what she says.. everything so she can trust me and i don't know why she wants to be with this guy.. he has a girl pregnant and well i don't know what to do..please give me some good advice.. i don't wana be impulsive and lose my little family...... :,(