Did he cheat?

[Alexageorge]

Hi this is going to be a long one. I'm just in need of a bit of advice as I have never got clarity on this situation and probably never will. Back in the 1st Lockdown me and my partner hit a rough patch. Stress and parenting got in the way so he took a bag and left after a big argument and went to stay at his dads. I wasn't expecting him to come back (not for a bit anyway) but he literally turned up like a day or two later without forwarning me and then just didn't leave. I then started to notice straight away that he kept mentioning a female (won't mention names) but she lived next door to us and just seemed really curious  (it could of been general curiousity) but something about it just didn't feel right. Like he started to ask me why she was talking to her ex more and I just kept saying "I don't know. Why are you bothered." In all fairness I didn't know why he was? But he wasn't doing a great deal to make me feel secure. Anyway this then followed by him randomly one night suggesting that "I go and take a drink round for her," and basically insinuate that I get friendly with her again so she didn't feel as alone. I did but he came with me and didn't let me speak? He did all the talking which I found really odd. Like he suggested this to me out of the blue (and it could of been a kind gesture) but I didn't need someone to talk for me? Not if he was insinuating that "I should try get friendly with her again." When I stepped back, it sort of felt like I was used as a 3rd party so to speak so it didn't look as fishy for him to just go take her a drink round out of the ordinary. Like I literally sat down and felt a knot in the pit of my stomach and just felt sick. I've then gone to check on Instagram and they had both been active at the exact same time. Before he came back home I'd actually had a conversation with her and told her that I'd found him talking to someone (long story but I never got definitive proof about who or how many people because he deleted the source so I could never see) and she also seemed really curious at the time about it and who it was. She asked me on several occasions. The night I took a drink round I straight up set him straight about it and he got extremely angry (It didn't end well) So I basically plucked up the courage and told her how I felt the next day but she said she understood how I was feeling and there was nothing to worry about and that she was thankful I'd told her and that nothing would ever change between me & her and if I ever felt like that again to basically go back and tell her. Because we'd always got on really well before. But following on from that talk I endured months of her blanking me, dirty glances and just difference. Although she was still perfectly friendly with my partner? And for months they were always active on social media at the exact same times.... and in that period he became really distant with me. He says he was just feeling down but he wouldn't go near me or he'd shut himself off in the bedroom for hours and was just really cold and hostile. This went on for ages so there were also periods where he'd come home late when he started up at work or I'd notice that they'd both leave the house around the same times and sometimes he'd just be nipping to the "shop," but he'd be out a little while longer than expected. I told him several times to just leave but he kept saying he wasn't going anywhere until I sorted "my head out." as you can guess I was a phsyco, crazy, paranoid and just basically every name you can think of. But my gut was telling me otherwise and there was never an explanation for why there were months worth of screenshots of them being active at the exact same times. I kept saying I would try to understand if he told me the truth because I knew he was struggling mentally at the time, I knew things weren't great between us and she had split up with her ex ... and I like to consider myself an understanding person but still to this day he tries to say its all in my head. I just think it was too much of a coincidence in all fairness. 

I ended up splitting with him afterwards but things happened in that time and we're both trying to move forward currently. But this still swarms around in my head. Her ex partner is also more in the picture now so she's back friendly towards me now? But it just doesn't add up to me because why did she act cold towards me for the whole duration of time everything was happening? At times she would literally give me dirty looks. But be friendly with my partner? Would you say they did have an "affair," even "emotional," behind my back? I will never ever be able to prove it. All I had was the evidence of their social media activity and he swears down on his dads life that he didn't (which I can usually catch him out in lies for) I want to believe him but how would it be genuinely possible to log out at the same time for months and months every single day all day .... if they weren't talking? 

Also to add on he will barely talk to her now ... whereas before all of this he would have long overtly friendly conversations with her outside our house.