I don't think I'm much of a source for sage advice, but I can at least relate to your struggle. I'm 23 also
I lost 80 pounds or so in 2008-2009 (in a year and half), and gained all but 5 pounds back in 2011. I was the only overweight person in my family, and they were all so proud of me when I got thin. I started identifying with being "the small girl," to the point where I got obsessed with staying too thin for my body... Anyway, 2 years or so of restriction finally got to me, on top of the depression and anxiety that I've dealt with my whole life, and I binged daily for several months. My point is that it is extremely important to really take a look at the things that derailed you. It looks like you already have a clue of what happened -- you had a lot of emotional turmoil to deal with from a bad relationship, and then ended up in a relationship with a man who you were planning to marry and found out he cheated on you. I think that would drive a LOT of people (myself included, I think) to turn to their drug of choice. It's great that you didn't turn to alcohol, or worse, but food (especially carby food, if your oh-my-gosh binges are anything like mine) is still incredibly addictive and also tends to make emotional problems a worse instead of better. I'm sure you know that already, especially since you managed to lose >90 pounds once before, and you can't usually comfort yourself with food a lot while you're losing weight.
You can absolutely lose the weight again and keep it off. I have lost a little over 20 pounds since regaining all that weight, which is less than a quarter pound a week and perhaps not a total "success," but I don't feel like I'm hanging on for dear life and about to lose control at any second, like I did when I lost all the weight the first time. The thing that has helped me the most is something that I borrowed from Intuitive Eating- mindfulness. When I enter binge-mode, I generally turn my mind mostly off, which is a big part of the allure of bingeing in the first place. So, I made a commitment to myself to stay mindful when I eat junky food or a large quantity of food. I'm still "allowed" to do it (and believe me, I still do it sometimes), but I have to pay attention to how it tastes, how it makes me feel when I eat it, and how I feel in the following hours. Since I usually feel crappy enough as it is, being overweight and depressed/anxious without medication, I am really starting to prioritize avoiding things that make me feel even worse. It turns out that this is a better motivator to me than just wanting to be thin. After all, I was under 100 pounds for over a year and I was still depressed and anxious, even more so because I put so much pressure on myself to have perfect self control. So, now, I'm trying to exercise self-compassion instead of berating myself like a sadistic drill sergeant. I pay attention to how good my body feels after I go to the gym, and I think, I
deserve to feel good like that, and so that helps motivate me to work out. Sometimes I daydream about eating a pint of Ben & Jerry's, but now the daydreams are usually cut short because they are accompanied by the feelings of sluggishness and depression that I know would come after consuming that much sugar.
I guess my main advice is to really try to be kind to yourself (which includes your future-self, whose fate is being decided by every action you take in the present), and focus on small improvements in your daily routine instead of the big picture of needing to lose 90+ pounds again. I don't think you necessarily have to get to a certain number on the scale to start being the person you want to be, so my last piece of advice is to NOT put your life on hold while you lose weight. That's easier said than done, and it's pretty vague because I don't know what types of things really make you happy... but I just wanted to say that your weight does not define you or how good/successful you are. You're not a statistic. You seem like a lovely person, and I have faith in you.
Good luck with your journey.