I have also been coping with many things of the past 2.5 years; it has been very stressful.
You can't "Try" meditation/yoga nidra over a short time and expect to be doing it at a high level. It may take many years to make progress on them, but don't give up. Keep working on them. The dividends will definitely come.
Ideas that may help:
1. be in the present moment. (I.e. be mindfull) This is the most important things that one can do. In order to do that one must accept reality. One can't change the past, it has already happened; so don't worry or stress about it. Accept it. Learn from it; use it an opportunity to grow. If you don't accept it, that will cause all sorts of mental problems. Also, don't worry about the future, you don't know how it will unfold. Don't make the assumption that it will be bad. The key is to stay in the present.
2. Breath using your diaphram. I.e. belly breathing. Lots of times when stressed or nervous one breaths only in the upper chest, which will add stress to the body.
3. Pranayama - yoga breathing exercises. These should balance one out and help one calm down. Alternate nostril breathing to balance out at the start of pranayama or yoga session. (One needs to do the clearing practice.) Then move practices to calm one down. For example, exhaling longer than inhaling is calming. Generall a 2 (exhale) to one ratio (inhale). You should get an experienced teacher for this. It can do wonders to calm one.
4. Keep doing exercise that is physically tiring that will help burn up excess energy.
5. Some times when one is stresed, tension will build up in the body. That is where yoga asana comes in, it can help remove the tension by stretching the muscles that are tense/tight. This also bring up the point of trying to recognize how one's body feels. Can one feel the emotion or stress in the body? If so, try to release it. (whether mentally or by physically stretching) I found a relaxing meditation that did a body scan where it had one mentally release tension as one scanned one's body when I had trouble sleeping one time. It helped me sleep, I noticed that when I woke the tension in my lower back was greatly reduced or gone. The mind can definitely relieve tension on its own. I would look for a yoga teacher that can apply ayurvedic practices to the yoga.
6. Try a weekly deep tissue massage.
7. Try flotation station (isolation talk filled with salt water). I have only tried this a couple of times; it seems very relaxing and helps to remove tension from the physical body.
8. Try a therapist. If nothing else, it is a person that one can dump whatever shXt on and talk about as opposed to burdening a friend or family memmber.
9. Two books that I have found very helpful for one's mental state:
- Untethered Soul by Michael Singer
- Power of NOW by Ekhart Tolle
They are geared to help one be in the present moment. I read them in that order and recommend that order. These are not quick reads, one will need to think about them deeply. If you only want to ready one, then go for Power of NOW.
10. Socialize. Do something in the physical presence of other people. Do a jog or hike with somebody. Take your dog for a walk regularly.
11. Cut out media and do other meaningful tasks. This means internet, TV, streaming, phone, etc. A lot of the media is geared to get one addicted and stirred up. Whatever has happened, is already in the past and one can't change it. Get a feature phone that only does talk and SMS text (or disable other features), then one will not be addicted to it like crack.
12. Don't avoid doing stuff. Avoiding stuff difficult to deal with will likely make it worse. Deal with it get it over with and move on to something that enjoyable. If one puts it off, it will keeping being mental burden that will keep crossing one's mind and pulling one out of the present. Also avoiding that stuff sort of is like not accepting reality. One needs to accept reality to be happy.