You might want to involve a protector of children, like Artemis or Erzulie Dantor, if you’re worried about his kid. If you’re hard set on obliterating him, but approach an initiatic guardian like one of those and ask them to move the kid out of your way, there’s a good chance it’ll get handled for you so you can deal with the dad.
My advice to you is to do this yourself; don’t hire anybody. This is because need is an important factor in magic, and a contractor doesn’t need to help you, and doesn’t have the feelings of needing to accomplish the objective. It is not worth it to spend any money, really, on getting other people to act on your behalf, because they are not as connected or entangled with the objective. If you’re going to throw cash around, do it to make sure that you have the right stuff. Bluntly, nobody you could hire will want him gone more than you, and the level of ‘gone’ most people talk about isn’t the one I’ve been talking to you about. You may get someone to perform a real death hex on him, but that’s beyond the capabilities or willingness of majority (you will notice there are no ‘hex testimonials’ anymore at least), and even then, I’m talking to you about a finer quality of destruction.
The only circumstance in which it makes explainable sense to hire someone is to divine on most successful courses of action for you, and if they know anything, they’ll be able to give you a general compass to follow if you just say ‘I’m wondering how to navigate this situation’. Don’t go wasting your money, when you could practice intensely for only a little while really and come out ahead of most ‘professionals’ in raw output.
The feelings you described as experiencing daily are a more powerful pattern than most hired sorcerers will get you. IMO it is only fair that you engulf this pattern and it’s maker, but, to do that, you need to do the magic yourself.
@987ritual is correct in that you have to see this person as essentially your equal, the same stuff as you but another flavor, because acknowledging the shared human element is how you anchor the result to their bodies/socially perceived self. “The first rule is to always face your enemy”, and all that; you have to see yourself through their eyes to be able to shut theirs. Putting people on a pedestal or in a pit creates inherent animal judgement about them that can leave you a bit sideways. You have to look at their face to peel it. 
987’s also right on the terms of people not really being separate entities, @duskwalker , but in the same way you rarely address your hair by the individual strand; it’s a collective of esoterically and functionally self-same stuff. Until you have put enough magic into yourself to fundamentally alter your energetic behaviors, you are resonantly human- which means that ritually, working on another human creates a feedback loop, which is why there are methods to ‘reverse’ magic as if it was a car or trajectory, as well as methods to protect yourself from blowback, detection, etc.
In the rawest-to-reality sense, the only time there is registered differentiation in the mass of human consciousness is when it is magically patterned; we are given identity by our rituals.
OP, I honestly haven’t had a haunting like that, but karma is real (it’s not moralistic like most people would have you believe, just a property of energy echoing into and out of your self/life; it can even be affected by seasons) and erasure is actually one of those events that has a kind of neutral pull in it, partly because it’s a universal act, and partly because total erasure done successfully circumvents negative possible side effects, because those arise from ‘scraps’, of which erasure does not leave.
Let’s drop all pretenses here, this is a world without justice. Virtue has no inherent power. We find meaning in the blood we shed. Justice is not a naturally occurring phenomenon, but always shows up around blood; we make it out of each other.
My recommendation is to stop listening to the people who are trying to ‘correct’ you, I’ve learned never to judge someone until I’ve walked in their skin, and that you can accomplish some pretty great things by addressing reality directly, your way. The only point of Etidor’s I agree with is that you should have absolutely no fear of the consequences before you even think about performing the ritual, because, take it from someone that learned the hard way, that fear will bite you in ways you can’t predict from the onset. The only way to protect yourself from it is to erase it, aka ritually externalize and murder your fear.
My last bit is that you should stop treating this as a corpse you want to create, even if that is the intended effect. The idea of a corpse is something relatively new in human history, but what isn’t, is a prey animal- just a thing you need to crush to keep on living. If you can synchronize with that ancient hunter mind, and view your target as a moving thing to take apart and fill your belly with, you get a much deeper ‘tone’ to the curse. Erasure isn’t about making someone into a corpse, it’s about removing something to perpetuate or continue a cycle (aka your life).
. Trust, I’m going to internalize everything you’ve said.