I realize that we should never let our friends down.
个人觉得前面用realize比较好,你本来不知道,现在知道了,就是realize,比如你用 I get a point that...就比较中国化了,望采纳。。。
I understand a truth, never let your friends down
I understand that we shoud never let our friends down
Finally I understand that we shoud never let our friends down for good.
I have learned a lesson that never ever let your friends down.