I’ll do my best 0294 45 To woo your lady. ⌜Aside.⌝ Yet a barful strife! 0295 Whoe’er I woo, myself would be his wife.
Viola's "aside" part reveals what she is truly feeling inside, her internal struggle : she must help Orsino "woo" Olivia, meanwhile she is in love with him. "barful strife" reveals the emotional and social obstacles Viola faces. It is a very poignant expression of this unspoken love, and deeply highlights the theme of identity and disguise.