Let go for good?

So me and my boyfriend of one year broke up a few days ago, he blamed it on his mental health and that he doesn’t want to be in a relationship with ANYONE because he just wants some time alone to sort himself out, I can understand that and I respect it. I have been a total mess ever since that day, crying non stop and just heartbroken. The day after we split I was scrolling through Instagram and saw he commented on another girls post calling her gorgeous, which he never once done for me he basically hid me. Anyway I let that one go, he is now flirting a lot with my best friend. The one who was always with me and him. Obviously I trust her and she says I have nothing to worry about but the fact he would even consider that?? Also, he told me he’s perfectly happy without me, I wrote him a big paragraph explaining my feelings and how much I love him and he replied with “ suck me off”. My friends tell me to block him but I feel like if I do, he will think I’m weak but I also want him to realise that I’m gone for good. Although I feel like I shouldn’t block him so that he can see me being happy without him? Idk what to do please help me lol