I will agree with getting some VG to cut it with, but have a few additions:
Make sure you get USP-grade VG or higher. Never get anything lower. USP-grade is foodsafe. There is supposedly medical grade above that, but I have never been able to find it for sale, only USP-grade.
It will not only reduce your nicotine intake, but it will also reduce whatever flavoring is in the juice. Thus, I strongly recommend to test in much smaller doses so you don't destroy an entire bottle of juice or make it unvapeable to you.
Inhaling into the mouth, and then drawing in clean air while inhaling it further from there, does cut down that slam to the back of the throat a bit. Drinking water is also a requirement... because both PG and VG will dry you out and dehydrate you a bit when you're getting started.
Things that tend to increase throat hit for a lot of people are a higher PG content and a high nicotine content. In the juice you described, you have both. Some people also get a throat hit off of different flavorings, but that is incredibly variable.
Hope that helps!