All the errors

Not according to plan

Regulus Pov:
"Dear diary, we have been dating for a year now, Sirius still doesn't know, but I feel kind guilty. This is his best friend and his little brother. What is he going to say? The longer we keep the secret the more mad he will be!"
"Reg, just come back to sleep." James begged as he pulled me down. I sighed and laid down.
"So, what are you writing about now?" He asked me. I laughed.
"Just about sirius, and how he will react." I answered.
"He's going to freak out." I explained.
"Reg, he won't be that mad." James told me.
"You don't know him like I know him." I said
"I'm pretty sure I do." James answered with a laugh.
"James!" I hissed.
A few years later
"Dear diary, me and James have been dating for a few years but but Sirius still doesn't know. I messed up. I really messed up. We love each other, but I made a mistake that will be the death of me! I.... I became a death eater... he's gonna like me for it!"
"Reg! Come on we are going to hogsmade!" James whispered in my ear as he passed, we were heading to our common rooms.
"I'll meet you at the 3 broomsticks in half an hour." I whispered back and headed to my common room. After a few minutes we were in the 3 broomsticks talking, and drinking butter bear. We were talking about how we would tell Sirius.
"Well then, this is quite the show isn't it, Reg James?" Sirius hissed from the door, we both turned around and he was with Remus and Peter.
"You know what, me and Peter will meet you at honey dukes." Remus whispered and him and Peter ran off. Me and James got up, quickly paid, and went outside to talk to Sirius.
"Sirius, we can explain!" James said
"No, no no no, I don't want your explanation!" Sirius hissed to him.
"I want to know his excuse." He said pointing at me.
"W-what? What excuse?" I asked, confused.
"Oh you know! James, has he ever abruptly left for a reason that he couldn't say but just to trust him?" Sirius asked James.
"Yeah sometimes, what are you getting at?" James asked him.
"You know what that's all I needed to know." Sirius said.
"James, go meet up with Peter and Remus at honey dukes." Sirius told him and turned to me
"I- Sirius! I swear, he, I," James stammered.
"No James! This is my brother! Hell, my YOUNGER brother!" Sirius hissed.
"Sirius!" James said back, trying to explain.
"Sirius please just listen!" I asked him.
"You don't get a word in this!" Sirius hissed to me.
"Just go James! I trusted you!" Sirius hissed to him, with a hint of sadness in his voice.
"I..." James was gonna say.
"James, it's fine." I whispered as he finally sighed and gave up.
"I can't believe you! You date my best friend, you get the dark mark, what's next? What happens when we join different sides of this war? When you have to kill James for him!" Sirius hissed to me. I stopped, knowing he was right.
"What would happen, will I kill him? Will I stop myself? Will I, what will I do? Some many options, so much to go wrong!"
"ARE YOU WRITING YOURSELF NOTES!" Sirius hissed to me, now pissed.
"I AM TRYING TO SHAME YOU!"he hissed.
"Sirius, your better than this!" I told him.
"But are you? I want my friend to be happy, not heartbroken by my younger brother Reg!" He hissed to me, and left.
"That was that, he yelled at me and went to Honey dukes, leaving me left alone, outside of the 3 broomsticks. I couldn't take it. I betrayed everything left of me and Sirius trying to act like brothers, I failed myself, I failed James. Who would I fail next? The dark lord? Bellatrix? Narcissa? Andie? Mom? Dad? Aunt Druella? Uncle Cygnus?"