Well i seeked this group because im goint through a hard time iknow theres people who have it worse but this is my worse : (, im new to divorce marriage everything, and i am super lost i dont know what to do or what road to take....it feels really bad...

Long story kinda short: im 27 my soon to be ex husband is 39..we have been together for 4 years and was going on 3 years being married... its going on 3 months he blamed me for not being at a camping trip he "planned" and disapeared for 4 days that weekend, hes a truck driver so he was only here for those 4 days that month, the day came he had to go back on the road. A few days later he texes me saying its not working out and i can stay at the apt (which i am also on the lease) and he'll pay everything to make it easier on me. I couldnt believe it so i went off on him, throughout the month he was gone he would text me to find out if i was still at home, when was i leaving and why wasnt i gone yet...i packed my things, but decided to wait for him incase there was any hope, he got back home in october ,when he got back since i wasnt home he send me some nasty texts while i was at work: why was i still at the apartment and why hadnt i left yet if i had friends and family to help me. I got home and we confronted eachother he threatend to put my stuff outside when i got home from work the next day and i needed to leave that night. The next day i went to work thinking my stuff is going to be outside i was scared, but friends said no he cant do that he will get introuble (he is on probration at the moment for other things) so i stayed at a hotel that night to cool down and i just wanted to be alone to think, the next day knowing he wouldnt be there i went in and grabbed as much of my stuff as  i could and took my puppy, i didnt get any documents they were all left behind, he text saying he trew what i had left behind and that was the end of it. I was holding back on filing for divorce because i wasnt sure if it was just a phase or what was going on, just yesterday i found out he is back with his ex that left him before we started dating, i found out they have been together for 3 months now and i understood everything, all the lies and his attitudes and questions i had about his behavior had made sense and started falling into place.. it feels horrible! She is staying at the apartment...i dont understand how he can do all that  but i still havent received divorce papers from him ??? its a very very horrible feeling... So i said to myself no more waiting i need to file for divorce asap. But i dont know where to start...i feel lost and confused..i wish i can get back at him so bad but i believe in Karma...