i am really struggling

i’m having such a hard time. i’m begging someone to listen to me and help advise me, or encourage me. anything. please. i have a one month old, and a 4 year old. their dad left me to get “clean” off of drugs when i was 38weeks pregnant, and i went into labor two days later. i did it completely alone, scared out of my mind. our son has abnormalities and was high risk pregnancy and birth. nicu stay immediately following birth. we knew this. nothing went to the plan we had for months. i say clean in that way because he isn’t clean at all… his whole reason to leave to his moms to withdrawal and be clean then come back to us to be better and there for us. his drug use is worse than ever before. he always has been a great parent but not anymore. he is completely absent. he doesn’t care or love his kids anymore. he is a stranger to me. i don’t know this man. he went to his moms to get clean, well he doesn’t even go home anymore. she told me he decided to leave: he lost his job. he isn’t worried about working. he is seeing random females and sleeping with them. he is either living in his car or bouncing from female to female. he gives random people rides for money. he doesn’t talk to me at all, besides when he needs or wants something which is money or to blow my phone up for the door dash code because i keep changing the password to lock him out to not enable him further. he doesn’t support our kids financially or in anyway possible. he doesn’t see me or the kids, he doesn’t ask about them or if im okay do i need anything for the kids or myself. i didn’t expect my life to be this way right now, i love my kids more than anything and that’s why im still going. but it’s all on pure hope that this is all going to pass and things will get better but i honestly see no light at the end of the tunnel. my four year old is sick and got my newborn sick. he isn’t sleeping at all. he is up almost constantly i’m talking 4-5 hours at a time, sleeps maybe 1-2 hours since being sick. and she is too (4yr old) my newborn needs to be constantly held won’t use the bouncer, the swing, won’t lay in the crib. im breastfeeding, but mostly exclusively pumping so im never getting a second to breathe or relax. to sit down for a second. or not be touched or overstimulated. im exhausted. im so drained i have nothing left but somehow i keep giving because i can’t give up and i can’t stop going cause i have my kids. i can’t believe this is happening in my life. the amount of hurt and betrayal from my kids father is unexplainable. i have spent 8 years with this man, my whole adulthood nearly. i’m only 25. he is 33 years old. he has held me back for so long i know him leaving was for the best for me and my kids, especially with the drug use. the cheating. but i just need some help. my mom is in bad health and she helps as much as she can im so grateful for her and for her to be here for me but she can only do so much. she has a bad heart and actually had a heart attack 3 days before him leaving and me going into labor. she kept my 4 year old for two weeks straight while i was in the NICU with my son all while trying to recover from her heart attack. i cry everyday. the times i do talk to my kids father which is rare i’ve poured my heart out over and over. i am just dealing with so many things at once and i still love this man despite all he’s done to me. i feel incredibly stupid. i’m having a hard time letting go of him even though i know it’s what’s right and best for me and my kids. i had shared so much of my life with him. i’ve shared two babies with him. i am betrayed he doesn’t love his kids or me enough. i’m at a loss of what to do. i hate that i still love this man and that even if their was a 1% chance of him changing and turning around completely im scared i would take him back cause it’s so hard to let him go. the drug use, cheating, manipulating, he has been emotionally, physically, and verbally abusive for years. i can’t have social media but he can. i can’t dress nicely or do my make up or hair. it’s been a lot yet im so dumb to stay for so long and have two kids. i love my kids more than anything they are a blessing. but i’ve wasted so much time and energy. to still love this man and struggle to let go. it’s so hard doing this alone with my two kids, i didn’t plan for this or expect this at all it was always both of us. if anyone can give me advice , advise me, encourage me, just listen to me vent, anything. i’m about to crash out. i’m at my limit. i need help. i don’t know what to do or what the answers are. i’m hanging on by a thread.