how can i start to appreciate myself again?

alot has been going though my life lately and now i just isolate myself from almost everything. i have a boyfriend, and cheated on him by letting this guy i used to like kiss me. i regret it 100% now and me and my BF are going through some hard times because of it. but now i am not the same person anymore, i just try to regain his trust and strong love like how it used to be before. so i don't hang out with any friends anymore, i hate my home life, and feel hopeless in my relationship with my boyfriend. i used to be funny, love to laugh, everywhere with friends, close with my mom. but now i just like to be by myself all the time, and all i do is cry until i sometimes fall asleep. im only 17 i don't think i shouls be like this, especially my senior year in high school. going to college feel like a drag to me or like it's going to be a bore,just go to my classes and not be involved in anything. im scared to do anything that will make my boyfriend think im doing something, or make him unhappy so i avoid everything tha's fun or relaxing or just normal for a teenager. so far it makes him feel better and less worried and calm, but it has caused sadness and depression for me, and im missing out on everything, im even scared to talk on the phone with anyone but family, so my BF won't think i was talking to some guy. so me and friend don't talk on the phone anymore.all i do is cry now. so how can i feel better or try to feel better? help anyone