Is it normal that i feel completely obsessed about my boyfriend. ........

Hey people! I registered on this site, just for this...
Basically, i begged my boyfriend to come back to me after i dumped him for having online sex.. im not sure how that happened, i hope what you read here can give you a glimpse into my craziness and maybe i could get some opinions.
I love this man, but im not sure i trust him. Is that normal?
because I don't know what step to take next, I feel like i have no independence, i have lost my friends, i only see my family in the day because he pics me up every night after work. I am totally in love with my boyfriend. We have been together for 3 years and this is the first night in 4 months we haven't been together.
When we first got together this was the other way round, I even moved into a flat with my friends about an hours commute from him, i was totally independent and he seemed to hate me for it, but i always argued with him, telling him i was at uni and that i was allowed to do my own thing and he stayed with me regardless.
Then something started to change, i started going round his house and skipping uni to go and see him and he didn't mind that i wasn't doing well there, he just said he would support me no matter what, one day i was at his house playing on his computer and a girl pops up in 'Skype' chat, starts talking about sex.
This before i go there, was 2 years into our relationship, he never physically cheated on me, but i read this conversation that popped up and my heart broke, it wasn't just one girl, it was like 5 girls and men, all in different conversations. I broke up with him.
I dont mind guys looking at porn, but what i do mind is when my boyfriend is getting to know girls over the internet, having weird online sex with them, and men? this is what confused me.
I moved away again, after we broke up and didnt see him for 2 months, until i came back, and i felt like i was ready to move on from what he had done. I might sound stupid to some of you, but i love him so much, if i could forgive him for what had happened it would be amazing, because i thought, i would never argue, miss an opportunity to be with him again, i missed him like crazy and i didnt want to admit it because of the digusting skype stuff, but i did forgive him.
Anyway. We are back together and the dynamics of our relationship totally changed, he is angrier, more demanding, more confident with himself, i used to be so confident like he is now, but i am not anymore. I am afraid if i do something wrong he will leave me, that im not good enough, i feel like its always my fault, at first i go to argue with him then think no its me being an idiot again, but i think that everytime?! he must do somethings wrong. I am jealous of him and his friends. I dont even want to think about losing him,i am obsessed with him. I get obsessed then after about an hour of being like that i distract myself and im fine, then i feel bad. I feel like i am never doing enough to make him happy. Im scared of him sometimes, he loses it, and gets so mad and he has never hurt me but hes smashed stuff and drove dangerously and thrown stuff and he shouts at me... I know he sounds really terrible but when he is nice, he is just lovely which i think is most of the time, but i just cant tell, i feel like i know what he is doing and he is being mean, but I also feel like, he loves me.
i don't know what to do anymore. While writing this i have checked my phone like 4 times to see if he has called... i mean that is ridiculous.
ps, i do know that he loves me, i just feel like he doesnt care sometimes.
whatever you do please be sensitive, because i take everything quite personally amd what you say will effect me.