AIO my girlfriends ex has been harassing me for two years

These screenshots are just from ones I received yesterday. I usually receive them about a couple times a month. At first it was everyday for about 6 months when I started dating her then he slowed down and came back to harass me more for two years… I feel bad for him cause I think he’s mentally unstable but I just don’t know what to do to make this stop and have accepted a while ago that it won’t ever.