Please help. I really need an honest advice😔

Last year I was with a guy. A short-term relationship but full of happiness. At least this is what I thought. Although we were talking about marriage, on Christmas day, he sent me a text "Merry Christmas! I'm back with my ex. Our thing is over". I've never felt so bad and humiliated. I had a huge shock and can't remember anything that happened until the 27th of December. On new years eve, he texted me to tell me he is off with his ex too. I was so stupid that I thought one day he will be back with me

He started o date women, but continued to like and check my social media posts too. On August, he posted on fb that he is with someone. And at the same time, his mother contacted me to tell me that she just wanted to make sure that he will never come back to me because he always does what she wants. And she wants that girl. I've deleted them both of all social media and I thought it's over. However, even though his friends tell me how happy he is, he keeps checking my stories (I didn't block him) and his sister still tries to talk to me. I don't know if it's because of Christmas coming, but I feel so empty and lonely. I feel like this guy took the life out of me. I don't trust anyone, I left my job and although I was on dates, the thought of being dumped on Christmas again, kills me. Please give me an advice, as I've tried everything... I don't see any light.