Search Results: being a rebound

So my ex and I hit that 4 month mark. Well after back and forthing with him I decided to completely ignore him. IN Which He Got Angry. 3 or so weeks ago he told me he misses me, our closeness, stability, how we made love and didn't just have sex, and our possible future. We actually connected again and etc . During the 4 months he has been drinking off the wall and having sex with way to many girls. Even tried to with me in which the answer was NO. Well now he's made it very obvious that he is dating a girl who is from his hometown.(thousands of miles and an ocean away). I don't necessarily care if he dates we aren't together. But he has made it clear that he still cares and has feelings for me, but hasn't decided what he wants. He has also made if clear that he feels I guess guilty or embarrassed about how he's acting and the things he's been doing. And that I will love him less because of it. I'm not gonna give you this crap that our relationship was perfect cause it wasn't. But we were in love. Powerful love. I still very much love and adore him and do believe he and I connected on a level like no other. I'm wanting to know a few things. Is he serious about the whole missing me thing or is he just being an a$$? ( he said this on a different occasion then when he asked for sex). Is he just testing the waters (rebounding) with this girl or there no coming back? What generally would be going through a guys mind at this time? Should I completely let go or hold out a little longer?
*We split cause he needed space. And eventually we just broke up. He says didn't want it to be over which he said on multiple occasions

This is the letter:
"hey
sooo, i paid the bill off! the weight has finally been lifted 🙌🏿
i understand that youve been moving on with your life and im sure itll be easier when there's not a obligational burden attached to your ex lol
with that being said, i think its a good idea for us to finally stop talking. i dont have to tell you how i feel bc I've been honest this whole time. but im sure that by now, you see what i mean. I've finally decided that instead of going through this cycle over and over again, i should leave.
i know too much. i feel too much. a friendship between us wouldn't make sense anyway. i guess i always knew that, even tho it was something i wanted, but i wanted it for all the wrong reasons. i wanted to have you around (but i didnt), i wanted to gain closure (but i didnt), and i wanted you to come back (but you didnt).
unfortunately i held on&accepted things with hopes that you would find that there was still something here.
altho its part of what hurt the most, im proud of you for sticking with your decision. that takes a lot of maturity&im sure it wasn't always easy. but, you did what you had to do to be happy and thats all i ever want for you.
I don't know how many times i wrote this same letter to you, then hit you up days later. I've been so afraid of losing you, but im (finally) understanding that i been lost you. but, just like when you wanted to break up with me but you kept talking about us going on a break, i guess i had to just keep doing this til i was sure.
anyway, i wish all you all the best, always, and i pray that youve found your happiness within you."
Im trying not to act on my immediate feelings while also disregarding some info his close friend gave me; which was basically that he's not with his rebound (but ex has told me that they were just having sex, never in a relationship)& "just know, he's getting his life together". What would you guys do?