Well largeli, of course we should hate/abhor evil.
Rom 12:9 Let love be genuine. Abhor what is evil; hold fast to what is good.
And like you were saying I would think it is a real difficulty to separate the sin from the sinner and maybe that is why Christ makes it clear that we should love all, even our enemy.
Mat 5:43 "You have heard that it was said, 'You shall love your neighbor and hate your enemy.'
v. 44 But I say to you, Love your enemies and pray for those who persecute you,
v. 45 so that you may be sons of your Father who is in heaven. For he makes his sun rise on the evil and on the good, and sends rain on the just and on the unjust.
In verse 43 Christ says "you have heard that it was said... hate your enemy," that is not found in the OT, nor does Christ say it is, He's only saying it's been traditionally handed down to hate your enemy, but He refutes this idea. Paul teaches we should kill them with kindness.
Rom 12:17 Recompense to no man evil for evil. Provide things honest in the sight of all men.
v. 18 If it be possible, as much as lieth in you, live peaceably with all men.
v. 19 Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.
v. 20 Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head.
v. 21 Be not overcome of evil, but overcome evil with good.
I guess we should leave the hating to God, He is just and will repay appropriately.
mercy, peace and love
Kat