Welcome to the beyondblue forum. Great to see you reaching out for some support. I am sorry to hear that you are struggling with getting what you need from your relationship at the moment. It can be a really difficult time supporting someone while they are working through their own mental health journey. Seeing a therapist for yourself is a great step towards maintaining your wellness and having an external sounding board to be able to discuss how you are feeling. There are a few possibilities to be able to access support at a lower cost and I will suggest a few but there may be others depending on where you live and how old you are.
Your first step might be to visit your GP and get a referral/mental health care plan and ask your GP if there are any therapists around that bulk bill. Unfortunately there is often a waitlist to get these appointments.
Another option would use your Employee or Student Support Service (if this is available to you). These types of services are most often free and confidnetial.
Another option that may be available to you (depending on where you live) is contact the Developed by beyondblue NewAccess program. This is a FREE program that supports people with low mood and worry and you don't need a GP referral to access support. You can read about the program to see if it is available in your area by checking out the webpage here https://www.beyondblue.org.au/get-support/newaccess
Another way to get some support is by reading through the 'Supporting family and friends with a mental health condition (carers)' topic thread in the forum. There are also many other topics to review such as staying will, managing stress and improving communication in relationships.
There is also a lot of information on the beyondblue website about supporting others who are going through depression/anxiety. I have attached a web page for your convenience. https://www.beyondblue.org.au/the-facts/supporting-someone/looking-after-yourself
You are not alone in being challenged when supporting a loved one through their journey of depression/anxiety. Seeking out your own support structure is a great start and you have already taken this step by reaching out on the forum. This can be tough to do so make sure you acknowledge yourself for being so proactive in your own health.
Wishing you the best possible outcome,