How can I begin to feel like myself again

I think that you have to find out what has occurred and get to the root of the problem of what has made you feel like this and not yourself.  You have to find ways to regulate your emotions.  Depending on thoughts, it would be a good idea to challenge your thoughts and anxiety to start changing your beliefs and thoughts. You can do this by doing exercises to challenge the thoughts.

Most people think that this will happen right away, but this takes a lot if time.  If you have had negative thoughts for a long period of time, it will definitely take time to change those habits.  I like to compare it to exercising.  If one needs to lose wight it doesn't happen over night, it takes time and commitment to change that individuals eating habits and also putting the exercise in place.  Cognitive behavioral therapy is such that by really working you can change the negative thoughts and beliefs.  It is telling yourself that you are worth it, you are good at what you do and that you will succeed.  It takes a lot of time and even emotional energy.

I always help my clients by having them do this, but also journaling what they are thinking. It helps to really see the negative beliefs, and help them pick apart the journal in sections and go through it. We as a team are able to go through a journal entry and work through the thoughts, and are able to see a positive aspect to what they may have been thinking negatively.

I also think that if you are not comfortable anymore with your partner, you need to find out if you think there is a future with your partner.  If not, it may be hard to step away, but taking a break may be efficient to see if you can live without this person in your life. I think going back and finding what made you first fall in love with your partner is important.  If you are able to achieve that again, then maybe there may be a chance, if not then it may be time to step away.