How to tell your lover your over him?

Be honest. Try not to antagonise him- rejection is difficult and your incompatibility isn't your fault or his- but make it clear that things aren't working out. Try to hear him out and have a conversation; his initial reaction will likely be shock and his initial response might be a knee jerk reaction. By having a conversation with him, you can sort through all the difficult emotions with each other and separate amicably. Sometimes, though, the other person won't want a conversation. If he is too hurt to have a conversation without starting a fight, the best thing to do is give him space to recover, as staying in his space may be very painful.