It is indeed "in your head", which is absolutely normal. All tastes, good and bad, are in our heads, as well as most other things we experience. Taste is subjective, as are the associations we make with a particular aroma, and the general attitude we have towards an aroma (in your case, aversion).
If you want to start eating meat again, it shouldn't be too difficult to reestablish a positive attitude towards meat and start perceiving it as "tasty" as opposed to "dead animal, yuck". It is a very common attitude in humans, and there is some predisposition to like the taste, while the dislike usually has to be acquired. However, it will take a bit of time and training.
When you do this training, the last thing you want to do is to use tricks to distract yourself from the taste or mask it with marinades, spices or whatever. This way, you won't be training yourself, you will be reinforcing the aversion. On the contrary, you will have to make yourself experience the taste while being present, and try to explicitely acknowledge any unpleasant feeling or thought that comes with eating it, now and then asking yourself "is it really that bad". You will probably want to start with small doses, maybe one bite of meat per day. With time, you will relearn to enjoy it, but not if you shield yourself from the experience while you eat it.