I broke up with my boyfriend

I broke up with my boyfriend 2 days ago. We had a good relationship with many happy times but we also had a lot of arguments. The UK went into lockdown on the 23rd March and I asked for us to stay together at either his house or mine whilst this happened. Weve been together over a year so I thought 3-12 weeks would be fine together seeing as we stayed at each others most nights anyway. He said no but promised wed call to talk most days. He ignored all of my calls and never gave any effort back. He then proceeded to ignore me for 3 days and act like I didnt exist. He said hed been stressed and didnt want to talk to anyone but he was being very cold with me and I was obviously upset with him. I made the decision to end our relationship (over text as he wouldnt answer calls and we cannot see each other) and all he said was one word.. ‘fine. It was the hardest decision I made and It seems as though it hurt me a lot more than it hurt him. Not even 24 hours after wed broken up his ex girlfriend (from before me) added me on social media and I found out that they were messaging. I feel so upset and I dont know if they were talking whilst we were together as I sometimes thought something was off. Hed turn his notifications off on his phone and be very secretive about anything he was doing. He then deleted me yesterday, off of the social media that we normally message on. I still love him and I can't stop thinking about him, what do I do?