In chapter 50, it costs Aki 2-months of his life-span just by touching Angel's hand for a brief moment.
Let's assume that Aki only touches his hand for 3 seconds, 3 seconds of contacts costs 2 months of the lifespans, so it will cost around a year of your total life spans just to be in physical contact with Angel for 18 seconds.
Average male life spans is around 72.75 worldwide, minus your current age (average age of anime fan is about 18-25) , which means you have around 47.75-54.75 years of lifespans to spare,
47.75*18 seconds = 859.5 seconds
859.5/60 = 14.325 minutes
54.75*18 seconds = 985.5 seconds
985.5/60 = 16.425 minutes
In conclusion, you get to pound that angel bussy for 14-16 minutes straight before losing your life, which is more than enough for me cause I wouldn't even last 10 seconds in him