・・・、。
…Haah, how am I supposed to make sense of this situation, I wonder?
Literal
...Haah, how situation [obj-を] should-take-in [I-wonder-のかしら].
A reflective exhale. はぁ is the written form of a weary sigh — similar to English 'sigh' or 'ugh.' 受け止める ('to catch, to accept, to take in') is a compound verb used figuratively for 'processing a situation emotionally.' ~ば+いい ('if only I did X / how should I X?') is the fixed pattern for self-addressed 'what should I do?' questions. かしら is feminine reflective 'I wonder.' The whole line is a private moment of overwhelmed bewilderment.