Hi, I'd like to help you with your question.
It sounds like you have an enormous amount of stress to cope with and very little to no support. Handling adult children with special needs, anxiety and a relationship that is draining is overwhelming.
You said that you are already in therapy. Is it helping? You also mentioned that you are not motivated to get there. Part of the reason could be that it is not helping. Here is a link to help you find a new therapist or at least get a second opinion if you feel this is a problem:
If you are taking medications for your anxiety, are you taking any for depression? You may need a mild anti depressant to help you feel motivated enough to seek out the help and support you need right now. Ask your therapist about a re evaluation to see if depression is an issue. You may also need to have your medications reviewed to see if they are working for you. It is common to have medications adjusted or changed because your body becomes used to them and they are no longer as effective as before.
Also, building up your support system would benefit you. You mentioned that you do not have family close by and only one friend. You may want to consider a support group. Because of what you are experiencing right now with a variety of issues, you could choose whichever support group you feel might help. Here are some suggestions to get you started:
The stress of your marriage is also a big issue for you. Do you feel you want to try to repair it or are you feeling the need to try a separation? Depending on how you want to handle it, the best way to go about it is to seek out support so you can make the best decision possible. If you attend church, talk with your pastor. Pastors are often very helpful with marriage difficulties. You can also see if your husband is willing to see your therapist with you. Since the success of the marriage depends on your husband's willingness to work on the issues, you will be able to tell if you will be able to continue the marriage based on how he reacts to your request to seek therapy. Here are some additional resources to help you:
How To Save A Marriage: 92 Tips On How To Solve Your Marriage Problems Without Needing Marriage Counseling by Gary Vurnum
We Can Work It Out: How to Solve Conflicts, Save Your Marriage (Perigee) by C. Notarius and Howard Markman
Should I Stay Or Go? : How Controlled Separation (CS) Can Save Your Marriage by Lee Raffel
You also need time to care for yourself. The amount of stress and problems you are coping with is going to take a toll on you and make you feel down and unmotivated. If you face every day full of work and worries, then eventually your ability to cope is limited.
Try to plan something each day that you can look forward to. Even if it is just for 30 minutes, do something that makes you feel happy. Reading, exercising, go to a park or just sitting in a favorite chair and having a cup of tea.
It is hard to cope with stress but doing it alone is difficult at best. Reaching out and asking for help is a sing of strength and hope. It shows that you are interested in feeling better and that you do have the motivation to move forward.
Let me know if I can help in any other way,