About 3 weeks ago I got my 7 year old mare Bella. My first week with her was difficult, she bit me, kicked me, stood on my foot etc.
I mean this in a kind way, so I hope you won't think I sound harsh. First, welcome to the forum.
Now to me it sounds like you may not have enough horse experience to be working with a horse on your own yet. I'll say it definitely sounds like you need a horse that won't take advantage of your lack of experience, and Bella seems to understand that you don't know how to handle her yet.
An example that makes me think this way is that you say she stood on your foot. Almost any horse will stand on anyone's foot if they don't know how to stay away from underneath where the horse is moving. One of the first things taught to people who handle horses is to make sure you keep your feet where they won't step on them. Basically, if a horse steps on your foot it is nearly always your fault.
In my opinion, it would be good to get a horse that is supposedly more well trained and docile if one is available to you. However, you should understand that horses will not go on "auto pilot" and will need guidance from any handler. If you do not know how to give clear, consistent cues, any horse, even a well trained one will soon develop issues. An example again is that you were unable to stop the horse from eating when you were trying to ride. That would be something you should learn how to manage early on when learning to ride, and also the fact that she objects to being groomed might also mean you could use some lessons on signaling to horses what your intention is, reading how the horse is responding to you, and using your body language correctly.
Although she may have issues from not being handled much or being alone, there still are things that seem to indicate some lack of training on your part also. Yes, both of you are trainable, certainly. She probably shouldn't be trained by you, but perhaps you could have your own training with a different horse that is better suited to a beginner.