。
I know it myself, but...
Literal
Self [even-でも] that [subject-が] understand-[continuous-ている][explanatory-んだけど].
Trailing off with ~んだけど ('I know, but...') to leave the counter-point unspoken. 解っている is an alternative kanji for 分かっている ('knowing, understanding') — 解 emphasizes the 'solving/figuring out' sense. The sentence expresses internal conflict: the speaker knows something intellectually but can't act on it or accept it emotionally. Self-aware but helpless.