Feels like I'm going to lose it.

Hi, I been with girlfriend for about 7yrs now going on 8 we have 3yr old. Everything was going to plan I had proposed to her she said yes I was happy im finally going to have my little family. But not until recently beginning of May she gotten a new job and since then she's been so distant towards Me I understand with a new job can't be on the phone but I mean on your break or lunch call give me a call or txt so see how I'm doing or Check up on our daughter. Not until recently I just found out she had a social media account *** as of last month of June which we both agree we wouldn't have no social media at all since it cause so much problems...I had brought up to her about I check he friends list and its nothing but all of her co workers guys. She claims nothing is going on which I believe especially being together for so long she never done anything like this not until she started her new job..till this day she still hasn't giving me an explanation on why she made an social media account instead of talking things out she wants to break up with me then a few days later she wants to txt me saying how I'm doing like what do I do in this situation...I just want an explanation of why she did or if there is anyone else just tell me...I just don't know what to do im so lost and it hurts me more that my kid sees all of this im willing to work things out but she's still don't want to give me an explanation of her account.