I (M17) cheated on my partner (F16) and am being given another chance and need help/advice to actually change

So for some context, i’m not good at relationships as i’ve never let myself get attached to a person because i was always scared of getting hurt. in all my past relationships they had cheated on me and i guess i always ignored how it actually affected me. When i cheated it was online and no physical connection with a person, i was talking with the girl for about 2 days. i had then blocked her as i realized what i was doing was wrong and very obviously cheating. i guess the reason i did it was because i was scared that my partner would do it first as its how it always was. i didn’t believe someone could actually love me. My partner had found out and confronted me about it and at first i lied and said it happened before i met her ( i know i shouldn’t of lied and just told her the truth right away but i was scared of losing her in that moment and wanted to hold on as long as i can as i was sure she would of left) about a day and a half later i came clean and told her the truth and she told me it was over. I then decided to give her a little bit of space and called my mom asking for advice on how to navigate around this breakup because it was actually affecting me and i never felt that before. eventually my partner’s best friend added me to a call and got us to try again (my partner has told me that she wanted to try again regardless but her best friend quickfired it i guess.) and now me and my partner have talked lots about my issues at hand and ways that I can change and prove im going to give this relationship my all. but i just don’t know how to even go about it, i recognize my issues and do want to change for her but also for myself so i can become a better me by the end of all this regardless of what happens