Im really alone, and its my fault

Hello. Im trying to write here in order to find someone that can tell me “its gonna be okay”. Because i like to think that, eventually, it will. Sorry for my bad english.
My partner asked me for a break a Couple weeks ago, because we where on a streak of fighting over stupid things over and over, it really was exausting. One day i went though his phone (i know, thats toxic) and found a chat with a girl, with deleted messenges and heart emojis. When i asked about it, he just said it was nothing, and put the focus on me going throu his phone. After a day or two. He asked for a break, but i feel played during sayd time… he texted me when he felt like it, go see me when he needed to get laid… i felt used by the person i thought i would built my life with. On one of out meets, i asked “i cant go on with this uncertanty, i need you to take a decision, because this is tearing me apart.” He simply said, “i dont know what to tell you, i havnt taken a desision yet. After all the discusions and fights ive lost interest in being in a relationship.” But then, why are you still seeing me? Why are you feeding me with hope that maybe, if i find the right words, i could make you stay?
My therapist told me “You cant accept being punished like a child for having problems with him. You guys either fight for the relationship together, or you dont keep pushing the boat alone.”
Then two days later, i decided to put an end to the relationship and break up with him… but his response was basicaly “i accept it and i agree with you, you re the love of my life and i hope we can try again on the future.” This was on texts, when we meet to give back eachothers stuff, he told me “you didnt respect the break that i asked, this break up is on you. I didnt want to left, but you took the decision.”
Now im regrering everything. i feel like ruined everything…
Ever after that (two days ago) and ever since the break he asked for started, i find myself not being able to sleep correctly, i dont even have an interest in food… im taking antidepressants and started terapy last week, but i honestly dont know if im ever gonna be able to leave this loop of guilt…