Of course there is hope. Chin up!
You're feeling down now as a result of the end of your relationship and the fact that ex moved on swiftly.. you won't always feel like this.
Here's my tale of woe with a happy ending that should bring you some hope..
I was in a 7 year relationship in my 20's. Found out on my 31st birthday that he was cheating on me. I was devastated. Thought my life was over. It took time, but I got over it. I don't give him a second thought anymore. Don't know what I ever saw in him.
After I had picked myself up, I dated a guy for around 8 months until I found out he was married with a DD! Scumbag!! 
It's fair to say my trust in men vanished at that point. I remained happily single for a couple of years, just enjoying my life, spending time with my friends and family.
I then had a go at online dating. Met a guy on Tinder. We hit it off right away and had a whirlwind first couple of dates. I didn't realise at the time but he was "love bombing me". He reeled me in and I was smitten. About 3 months into the relationship, I found out the day after my 35th birthday that he was sleeping with his ex and other women!
(what is it with me finding out men are cheating on me on/near my birthday?!) I walked away but he then harassed me and I had to report him to the police.
At that point, I really did think I was sworn off men forever!!
I stopped looking for love and just focused on myself.
Then, I was introduced to someone through a friend. She wasn't even trying to play cupid. We got chatting, got along really well and exchanged numbers and the rest is history..
I'm now 37, we've been together almost 2 years and our DS is due in March.
So please don't give up. Your ex is not worth you feeling down and anxious. Forget him and concentrate on yourself.