need honest advice

i’m now 29 weeks pregnant and ever since finding out i have been severely depressed and i feel extremely alone. i’m 20 and live w my 21 year old boyfriend in our own house. when he was out of town for work i wouldn’t shower, do my hair, eat, i’d barely get out of bed. now that he’s back in town i do that stuff but only cause he’s here and i don’t want him to see me struggling as he has a lot of weight on his shoulders rn (he’s the main provider). a couple months before i got pregnant, he cheated on me by talking to other girls and i found out. we spent some time apart, not broken up, but i just couldn’t stand to even look at him. eventually i decided to forgive him and move on from it. he has put in a lot of effort to gain my trust but since becoming pregnant i’ve recently started to build this resentment towards him and i think it’s because i’m scared that once the baby is here, it could happen again and then not only is it just us but there’s now an innocent child being involved. idk if he’s doing anything. he does leave his phone around while he showers and i know his password and stuff but i haven’t gone through it in months and idk if he just thinks i won’t so he’s kinda stopped caring about leaving it around or if he’s genuinely not doing anything. i feel like i’m losing my mind. i spend all day of every week alone at the house just preparing for baby, cleaning, cooking, etc. i live 2 hours away from my friends and family. a lot of times i have to run to the bathroom to go and cry and then collect myself and come back out so he doesn’t know or i’ll cry myself to sleep in a pillow. i don’t have money to go see a therapist but i’ve never been so sad in my life & it’s driving me crazy. what should i do? (please no negative comments, that’s the last thing i need)