I was trying to be encouraging and positive. I guess tone doesn't come across very well when all you have is the written word, written by someone who tries hard but at the end of the day is not a great writer.
Yesterday, I watched a video by Melanie Joy entitled "How Vegans Can Create Healthy Relationships and Communicate Effectively" on YouTube. Melanie Joy is a social psychologist and vegan activist. At one point in this video, she talks about how unhelpful shame is. Having watched this, I picked up on the word "ashamed" in your post, as I might not have if I had read it on another day. That might have seemed a bit strange, but I was only trying to get you to feel good about going vegan again rather than ashamed of not having stayed vegan. I think it's important not to dwell on feelings of shame, which, in a very practical sense, simply don't help the animals. A few years ago, when it was much smaller, the vegan movement was more shame-based. Fortunately, attitudes are changing, and vegans overall tend now to be more focused on producing positive change and trying always to do better, rather than on feeling ashamed of not being perfect and making others feel ashamed of eating animals. It's a subtle but important difference, I think. The trickiest part is that non-vegans tend naturally to feel ashamed in the presence of a vegan, even when the vegan is going out of her way to avoid being judgmental.
If you're interested in the psychology of eating meat despite knowing where it comes from, Melanie Joy talks about that in her videos. I'm embarrassed by how much I've been mentioning her, but I found her videos recently and am in awe of her brilliance. Check them out if you have time and if you're into watching videos about veganism.
Let me mention that I, too, gave up on veganism for reasons very similar to yours the first time I went vegan in my mid-twenties. I lasted four months. I gave up because I had zero support from the non-vegans around me; I could see that I was not going to be able to stay completely vegan (I was about to travel to Japan for my research); I had trouble reconciling veganism's dependence on synthetics (i.e., plastics) with my environmentalism; and I was turned off by the fact that the vegan community at the time was totally focused on labels and appeared to consider anyone who was only 99.9% vegan and dared to call herself vegan as an evil hypocrite and the cause of all animal suffering. (In their defense, it's tough to be vegan in a non-vegan world that sees vegans as the problem. Things are a little easier now, with veganism growing so quickly.) So I gave up and went back to eating larger quantities of animals than I ever had before going vegan. Returning to veganism eleven years later, I felt really bad about all the animals I had eaten. So I get where you're coming from. All I'm saying is that if you want to be able to stick with it easily this time, it might be better to focus on the positive feelings rather than on the negative ones. For example, instead of thinking about how many animals you ate during the years when you weren't vegan, think about how many animals you're saving every day that you're vegan now.
There is so much honest self-reflection in your posts. That is rare, and you should be proud of yourself. You clearly care very much about doing the right thing, and animals are lucky to have you on their side.