The triple-threat entertainer hopped on IG Tuesday to both plug her just-launched spritzer line, Delola, and defend herself against fans who were apparently calling her out over it ... namely, the fact Jen has, historically, sworn off booze in the public eye.

Check it out ... Jennifer says she's aware of certain people raising an eyebrow about this business venture, and she addresses it head-on -- which also includes a confession.

She says while it's true she didn't drink for a long time while coming up, that changed about 10-15 years ago ... at which point, Jen says she began to enjoy the occasional cocktail. J  Lo says there's photographic evidence of this and that it's well-documented, BTW.

Another point of clarification ... Jen says she drinks responsibly and doesn't get "s***-faced." As she says herself, she just sips a little to be social and to relax/cut loose a bit. And as far as why she chose a spritzer as her alcohol of choice, she says it's light and relatively healthy.

One specific dig she did not address -- but which is certainly being discussed -- is Ben Affleck's alcoholism ... something he's battled for years, and which he seems to have kicked after stints of rehab, including a very famous one that roped in his ex, Jennifer Garner.

As we've reported ... he's had his ups and downs with alcohol, and JLo's been getting a lot of disapproval on that front too -- especially for advertising it on the 4th of July, no less.

Ben has said nothing about it himself, so you gotta figure he's on the same page as his wife -- and that Delola isn't a problem in the blended Affleck-Lopez family ... who looked quite happy and in sync this weekend.