Hi, i am really sorry to hear about your situation. I went through a similar situation last year just before my thesis was due with my then boyfriend (we were together for 4 years).  Along with writing my thesis, i was working at my job aswell as at a prestigious internship. I was just overworked and exhausted sleeping only 4 hours or less a night for several months. Then my ex who was a jerk to begin with (bad judgement on my part) just made the whole situation worse and treated me like crap like really badly and did some really horrible things and i fully thought i was going insane, crying all the time and just wanting to give everything up. However i would put on a brave face and go to work and university and stuff pretending like nothing was wrong.

I got to a point where i was just going nuts, so for two days i just went out to the park, shopping and doing things that i liked to do and just took some time to breathe.  During this time i took the time to reflect on everything and i realised what an idiot i had been crying over a guy who treated me like crap and wasting all that energy thinking about him when i could be using it to spend time with people who actually cared about me and concentrating on myself. Anyways, what im tryna say is obviously you are a bright and intelligent girl who has lots going for you (seriously how many people get into a PHD).  Don't waste this time over some guy who was not even worth your time to begin with. I know it takes time to get over someone you loved, but seriously life is too short to waste it on him. You are missing out on so much by dwelling over a guy who has clearly moved on. It was not meant to be and you should just accept it and realise that something way better is out there for you. This guy who is giving you lots of attention, don't feel guilty about it and don't compare him to your ex either.

I think you should get yourself into a routine with a schedule where you should excersise, write and reflect daily on yourself also if you are not already try going out at least 3-4 times a week and socialise with friends like have a coffee or something (it will help you to think about other things and have something to look forward to). Try and stick to a good routine it really helps! Also the best thing i found was to read novels to keep my mind off my ex at the time, getting absorbed into a really good novel helps or even a movie. Just try and keep yourself busy and focused get a hobby also wether it be baking, sports, charity work or anything you want to do. Anyways i know it takes time, it took me a while to get over everything but once i did i looked back in retrospect and realised how stupid i had been and that i actually considered dwelling over my stupid ex and wasting my potential and talents over someone who had the audacity to treat me the way he did. Don't throw your life away, you are worth too much! All the best and i hope this helps! :-)