Insecurities

I was previously in a domestic abusive relationship which lasted 7 years. I was constantly put down and made to feel insecure about myself after the split I was single for 2 years and I met an incredible man (so I thought). We have now been together just short of a year he constantly tells me he loves me and how happy I have made him. My mind can't stop wondering. We was sat on the sofa one evening when a message came through on his phone from another girl he deleted the number in front of me but since he has logged on to his social media accounts which he told me was deleted. Should I be worried or do I need to get over my insecurities any help would be much appreciated.

I'm a little confused, who was the girl who messaged him?

And he told you he doesn't have social media anymore, but in fact he does?

I am wary of anyone who lies about things like that, but we might need some more context.

He told me she was someone he knew years ago. He did have social media but deactivated his account just before we got together I am insecure as I have been messed around a lot previously and had my confidence knocked. But also he got a new phone a few months after we got together so unsure how she would have his number.