I suggest switching to vegetarian (lacto-ovo, so eating eggs and dairy) first. Or, if you eat a lot of fish, start with pescetarian. Maybe you could start with just doing a couple days a week vegan.

I can recommend vegetarian cookbooks, not so much vegan. For vegetarian, Deborah Madison's Vegetarian Cooking for Everyone is really comprehensive. Looks like there's a "New Vegetarian Cooking for Everyone" out now--and looks like it's 44% off on Amazon!

Something to consider in looking for other cookbooks is how you usually cook and what cuisines you tend to eat. I think you've mentioned a slow-cooker, so a vegan slow-cooker...cookbook could be good (or for Instapot, if you have that). and I think you've mentioned making Indian food--that's a cuisine with a lot of vegan options, so a vegan cookbook geared to that is good.

It also depends on how you feel about meat substitutes. Some cookbooks rely more on stuff like that, which I'm not into, unless it's just like tofu in a stir-fry. That could make the transition easier, though, if you're used to eating meat frequently.