Second time was when my first girlfriend whom, like in your case, I thought was the love of my life and would marry. Back then, I was young; a bit arrogant (tend to think my thoughts/beliefs are the correct way to do things); thought honesty==saying things the way I see them without filter (not censoring things before I say with empathy) and worse, thought my then gf will put up with it. I was wrong. After a couple of years of putting up with my stubborn ways, she told me she's breaking up with me. It came as an absolute surprise to me and despite my pleas to her that I'd try to change my ways, she didn't buy them (she believes that people can never change). Since the apartment we lived was under my gf's name, I had to find a room in a city (San Francisco), which I just moved 4-5 months ago to follow my gf (she got a job in SF before I found mine). I knew no one in that city and didn't have a car. Because I graduated from college recently, I was relatively poor as well. My gf gave me 2 weeks to move out. I remember walking in the rainy, cold/misty weather of SF after work every day to look for relatively cheap apartments in SF, Daly City and Oakland (saw a couple of shady apartments). I even got flu and lingering cough in that period. Eventually, I found a room in SF and moved my stuff using Cal train (only took 3 trips total because I didn't have much). After moving into my new apartment, it took me six months to recover from the heartbreak. It took me a couple of years to completely get rid of her from my mind. It helps a little that during the break-up period, I was preparing for grad school applications (GRE prep, for example) and work, so I was able to divert my attention and energy to there.
The third time was when my second gf, the one I met in grad school, cheated on me in my fourth year of PhD. She took a job in PA; our relationship became long-distance for about a year; and she found a boyfriend at her new job, but didn't have the guts to tell me for (I think) about three months until I slowly figured it out. That happened in November and I had a terrible Christmas and New Year. I asked for a break from my PhD supervisor and he let me (because he knows that I am not going into academia and thus, I could graduate with just 3 papers to my name as the first author. This means, I just need to finish 2 chapters in my thesis summarizing previous research and can defend that). I was also financially supporting my two siblings for their college and I literally had ~$2000 in my bank account left. So I promised my PhD advisor that I'll come back and defend my thesis. Then I left the University town and took an internship in NYC, which turns into a full-time job. Because my ex-gf cheated on me, it was easy to get over her. I think it took maybe 3 months after starting my internship to get back to normal. I was afraid to get back to the dating scene for a year or a year and a half.
All of this to say that time will heal you. Hang in there. It's not the end of the world. In fact, nothing in life is until maybe we are in our dying bed or an asteroid is about to hit the earth. Take the lessons from your previous experiences and try to become a better person (e.g., don't repeat the mistakes you made in your previous relationships). There are more than one person in the world who can be your soulmate (since break-up with my first gf, I met at least 6 girls--I am not the kind of person who actively date/go on hook-ups--who I was able to connect emotionally (I only ended up dating two of them and the last of them has been my wife of four years). Relationship aside, I'd say that PhD is not that of a big deal. In the end though, we have to make money. It's nice to have a PhD at the tail of your name (I never use it to be honest because I dislike formalities/showing-off), but in the worst case scenario that you don't have it, it's totally fine. You got quite a bit of experience from doing research in grad school and you take the knowledge with you in your life, which can become quite handy in your career.
Know what is in your control and what is not. Focus on what you can control and try to achieve better outcome in what you can. Try to stay connected friends/family consistently if you have good relationship with them (if not, it's still okay; I didn't have any, but I survived, so can you). That will keep you from feeling too lonely sometimes. Also, feel free to do some exercise/establish workout routines for self improvement. I was able to do 100+ push-ups after the first break-up with my gf because I exercised and also took long walks in SF (around Golden Gate bridge park) while listening to music; these really helped. Most of all, please remember that this is not the end of the world. New (some good, some not-so-good) experiences await you and you just need to take whatever positive you can from this experience, and use it as a base to do better in the future. Stay strong and try to do the best in what you can control.