That is an unfortunate thing. But, id think of your health and weight loss before the ink. Tattoos can be fixed and rather easily! I have had two kids, fortunatly, none of my tattoos around my waist were altered in any way. And no stretch marks popped up in them. They grew as my belly grew and they snapped back to their original size afterwards without any distortion what so ever. Unfortunatly this doesnt happen for everyone. My husband (being a tattoo artist, himself) will be first to tell any tattoo client, genetics is the huge factor in this. Not everyone needs to worry about their tattoos getting ruined as we shrink...but some do. It all has to do with genetics and if you have good natural elasticity in your skin or not.
Try to keep your tattoos extremely moisturized as you are losing weight and keep extremely hydrated as well....this may help, it may not?! And in the end, when you lose al lthe weight, treat yourself to fixing your existing ink work AND make a treat to do some big fabulous piece on yourself to celebrate your new body!
Make it a gift to yourself and turn it into a positive!!!