Is my ex interested despite having a new gf?

My boyfriend of a year broke up with me in October, and we haven’t really spoken since (I was trying no contact but then he didnt engage very enthusiastically when I messaged after a month) though he does always like my social media posts. I was in his town in March and bumped into him in the street and suggested we went for coffee which went really well. Immediately afterwards he messaged to say he’d love to do it again whenever I’m next in town and I agreed. We continue messaging and he reveals he is ‘seeing someone’ but we carry on chatting replying to each other only every 24 hours or so but that’s now been going on for a month. Thing is three days ago he posted a load of photos with his new girlfriend (something he never did with me) and its become clear they’ve been together since about a month after the breakup and are much more serious than I realised. However the ex is still finding random reasons to message me and I’m not sure what he’s up to. Is it just that he feels bad knowing those pictures with his new gf would upset me? Does he genuinely want to be friends? Or is he using me because he’s lonely (she lives abroad outside of term time and term has ended due to the pandemic so they likely won’t see each other for a while)?

I can’t tell if him messaging is a good or a bad sign or how to use it to my advantage to win him back so any advice would be greatly appreciated!
Thanks!