@jackspawnz, Haruta and Fuyu are not biological siblings. In
Chapter 5:
What Haruta means in this chapter is that he still sees them as siblings, even though they are not biological siblings.
1.
兄妹だった という事実を振り切ったつもり だったが
I thought I had shaken off the fact that we were siblings.
兄妹だった
- 兄妹 (きょうだい) — siblings (specifically brother and sister)
- だった — past tense of "to be" (だ)
→ "(We) were siblings"
という事実を
- という — quoting or describing something (in this case, the fact that...)
- 事実 (じじつ) — fact, reality
- を — direct object marker
→ "the fact that (we) were siblings"
振り切った
- 振り切る (ふりきる) — to shake off, to break free from, to cast aside
- 振り切った — past tense
→ "shook off" or "tried to shake off"
つもりだった
- つもり — intention or belief about what one was doing
- だった — past tense
→ "thought I had" or "was under the impression I had"
2.
最後の最後でブレーキが かかった
At the very last moment, the brakes were applied.
最後の最後 (さいごのさいご, saigo no saigo)
- 最後 (さいご, saigo) = "the end" or "last"
- The repetition 最後の最後 emphasizes "the very last" or "at the very end"
で (de)
- Particle indicating the place/time of an action. Here it means "at" or "in"
ブレーキ (bureeki)
- "Brake" (borrowed from English)
が (ga)
- Subject marker particle, indicating that ブレーキ (the brakes) is the subject of the verb
かかった (kakatta)
- Past tense of かかる (kakaru) meaning "to apply" or "to be applied"
- Here, "the brakes were applied" or "hit the brakes"
Thanks for the chapter!