Analysis of Sonnet 119: What potions have I drunk of Siren tears

What potions have I drunk of Siren tears,
Distilled from limbecks foul as hell within,
Applying fears to hopes, and hopes to fears,
Still losing when I saw my self to win!
What wretched errors hath my heart committed,
Whilst it hath thought it self so blessèd never!
How have mine eyes out of their spheres been fitted
In the distraction of this madding fever!
O, benefit of ill, now I find true
That better is, by evil still made better;
And ruined love, when it is built anew,
Grows fairer than at first, more strong, far greater.
    So I return rebuked to my content,
    And gain by ills thrice more than I have spent.