Advice about my relationship?

i m 25 yrs old and i m married to a 34 yrs old man . it was a love *** arranged marriage we know each other since 1 year and its only been 2 months since we got married . becuz of diiferent cultures and values we have different ideologies and so we have issues coming up everyday between us and our families as well. now recently i observed that his behaviour changed and him being sneaky about his phone msgs and calls . somehow i got the password to his phone and secretly checked his msgs and found out that he was talking and texting someone continously,had this person's name changed on his cellphone after one of his guy friend's name , going out for lunch and dinners wid this person. also telling that person how much he still misses her and loves her and same was from that person's side too.while going thru his texts i figured out that this was a girl obviously whom he misses and loves a lot.i was so shocked at this and confronted him asking if there's anything he is hiding and who was that person on his phone . first he lied to me saying its his male friend but when i talked about all the conversations that i had read thru he accepted that it was one of his ex-girlfriend but now he only talks to her as a simple friend and there's nothing going on between them anymore and stuff like that. when i asked him all questions abt why he dint tell me about this girl before and why he was lying to me and meeting her outside he replied he dint wanna hurt me and was afraid that i might feel bad and not understand his situation which is totally false becuz my husband had mentioned about his past relationships to me before our marriage and i understood them all and forgot everything moving on in our relationship. i asked him the whole story now and he told me everything about it and also said that there's nothing going on between them anymore. but when i asked him the question of why he was lying to me and meeting her up at cvs,gym, and other places and going out for lunch and dinners wid her even now he said he was just comforting her as a friend and making her feel better about the depressing things in her life and counselling her how to move on and not hold on to things from the past of thier relationship. after all this conversation i got so mad at him and so did he as i had broke into his phone without his knowledge and offended his privacy . anyways i forgave him for his mistake as he was being sorry about it ,now moving on in our relationship we dont trust each other anymore which is obvious and i m so stressed about our relationship . i dont know how to believe him anymore and trust him for what he tells me anymore just like he doesnt trust me anymore and changed his phone password and locked his files and documents from me. even though we both are trying hard to re-build things still there's something missing in our relationship. now we have this issue as well along wid other issues to deal wid in our relationship. i m so stressed and cant figure out what should i do about it. he asked for benefit of doubt and asked me to trust his words moving on which is so hard to do for me ,i cant see myself doing it specially when he already broke my trust at the first place. although i m not doubting and asking him where he is going and with whom still up in my head i m wondering what the hell he is doing and where is he now .things are not working out properly between us and its only 2 months of our marriage . instead of living and enjoying this new relationship we both have ended up in a mess .can you please guide me what to do about this whole situation becuz i cant live happily like this . i m trying my hard to forgive him and let it go and move on rebuilding my trust again but i feel like he is not doing his part to re-assure me for our relationship (although he says he is doing it ) and so its becoming difficult for me to trust him anymore. he said that he called his ex and told her not to bother him anymore as his wife has found out abt them but i dont believe him for this becuz he never did this in front of me so god knows if he is still talking to her more secretly now or out of it . can you plz guide me what should i do moving on in this relationship and also what should my husband be doing on his part to make things work and better between us.thanks