Can domestic abuse

No, neither anxiety disorder, nor childhood bullying, nor abuse in an adult relationship can cause ADHD.

ADHD is inherited in most cases. In rare instances, it can result from brain damage.
Some people, for all sorts of reasons, slip under the radar, don't get diagnosed as kids and thus don't get the help they need at the most crucial time to help in learning how to manage it.
ADHD can cause a child to become anxious because it can cause a great many seemingly random problems with poor judgement, forgetfulness, impulsiveness and reactivity. It makes relationships very difficult; loved ones who don't know the person has ADHD can't understand why the person has all these strange ways of miscommunicating - and it leads to tremendous arguments and conflict.

Adult ADHD can easily be diagnosed.
It's also the only neurological condition which is easy to treat - no cure, but the right management works extremely well. You have the prospect of a far better life ahead of you - and far better relationships with everyone around you.
The psychiatrist will want you to attend with someone who has known you a very long time, preferably one of your parents. They will interview you about your childhood and subsequent history, asking specific questions of both you and the person you come with. The parent (or long-time other) will have a different perspective than you do of yourself. The two views combined are crucial to the diagnosis.
You will be asked to answer 18 questions from the DSM5.
The answers will determine whether you do have ADHD and, if so, to what degree.
If you're positive, the psychiatrist will suggest a low dose version of Ritalin (or similar) for an experimental 6 months. If the diagnosis is correct ADHD, your family and loved ones will notice an obvious improvement about half an hour after taking the first dose. It is a tiny dose and has no effect whatsoever on people who don't have ADHD.
After 6 months, you will be seen again and asked how it's going. You'll be encouraged to experiment carefully with trying up to two pills twice a day, and see if there's a further improvement.
Over time, you'll be able to work out the best dose and circumstances for less or more.
Very rarely, a patient doesn't respond well to Ritalin, in which case there are a few other drugs which may turn out to be just right.

Ritalin on its own won't fix all the problems that arise from ADHD. You will need assistance to make practical changes - learning practical methods (new habits) for managing time and money, organising space, memory prompts and so on.
You may also need help with communication techniques (esp active listening skills).

If you're lucky enough to be in or near near a large city, you might be able to find a psychiatrist who specialises in ADHD. That would be by far the best. There are seven different types, which show up in mental and behavioural patterns, and on MRIs of the brain. The specialists can fine tune the practical strategies for your most dominant types.

I finally worked out that my husband (of 39 yrs) has ADHD when he was 73.
Later, it was confirmed by two professionals (inc. a second opinion.)

There are books about it by experts.
For your loved ones, I recommend, "Is It You, Me or ADHD?" by Gina Pera
For you, as one of the best introductory books on how to understand and cope, I suggest:
"Healing Seven Types of ADHD" by Russell Barclay

There's an amazing free online program about it by Edward Huberman - well worth watching.

Wishing you all the best.

Would love to hear back how you go and what happens - if you ever feel like it.

warmly,
Manna