Yes talk therapy would definitely be helpful and you shouldn't automatically rule out medication. Treatment has improved over the years and will continue to and very well might be of help. Speak to a talk therapist first and then you might want to obtain a referral to a psychiatrist after some time.
You've provided a lot of detail and that tells me you should benefit greatly from talk therapy as you have little problem raising these issues. That's a key element in talk therapy, being open.
You ask many questions so let's try to answer them for you.
Are you normal? Absolutely. About 1 in 4 people suffers depression/anxiety during their lives, not all their lives but parts of it. That's a normal thing today. Life has changed greatly from what it was even thrity years ago, with technology, terrorism and pressure on all things financial.
It would also be extremely normal to experience what you did following an abortion. 20 years ago particularly as even today there are people who will be nasty about it when it is simply your choice and life to do what you want with. Never let anyone tell you anything else.
Having an abortion at age 15 is more likely to have been the best decision for you and that child as young teenage mothers do not have great success in raising stable, well balanced children. Financially it would have been impossible and socially too. You did what you knew was best at the time. Decision made, justified and should be left to the past as it cannot be changed and there's nothing to worry about for you. Truly.
What causes your brain to create the thoughts you mention? Simple. Anxiety and depression do exactly that. It becomes like a soundtrack we hear internally. Over and over telling us we are worthless, the worst is going to happen and predicting the absolute nastiest things you can think of.
The truth is those thoughts are direct products of negative thinking which is part of the illness, depression and anxiety. Panic is another form of it, a nasty, shock trooper type.
I must say to you that religion does not and will not help with depression or anxiety. One major reason for me saying that is that the Bible itself is filled with predictions of horror and destruction and the most dreadful creatures whoever wrote it could imagine.
It's not a peaceful book I'm afraid and I'd suggest you read other books that are peaceful and harmless.
Nothing against religion, just if your mind is running off on tangents a Biblical quitation or two will trigger that very quickly. Leave t for Sundays perhaps with other people around you to normalise it and keep your thoughts on track.
The way to deal with this thought repetition and prediction is twofold. Talk therapy and/or medication. Herbal remedies are essentially useless and you've found that out haven't you. Waste of time and resources I'm afraid else no one would have anxiety or depression would they? Ever.
The key to turning those thoughts around is congnitive therapy. This is where you learn how your mind works, how and why thoughts start and how they translate into feelings and action. What we need to learn is to catch those thoughts as they start and challenge them and turn them back as we decide they are false predictions etc.
For example when we feel anxious we predict so many things will happen. Start by writing those predictions down and read them in a week. They will look silly. I did the predicting thing for so many years and never thought I had a chocie about my thoughts. I do and today I can pick up a negative one and reject it by replacing it with something positive. Took me a long time but I was very ignorant and stubborn.
The trouble with therapy, talk or cognitive behaviour (as above) is that if we are in deep anxiety and depression then we cannot absorb the learning and cannot practice it either. So we feel it is useless. SO the way to go is to lift your mood first so you can do the therpies rationally and with considered thought instead of instant reaction. Usually you need meds to raise you that much.
Meds do not cure you, they relieve symptoms and that is how you should use them. Relieve the symptoms, do the therapy and make the changes you need for a batter life.
Real easy for me to write this but it took me 40 years to learn it all. Don't expect to do it overnight but you needn't wait like I did, resisting knowledge.
Take your time, focus on the end result and make decisions instead of reacting. I'd suggest your husband should be doing all of this too.