What would you do?

Hi all, I'm not sure if this is the right place for this, but I really need some advice. Trigger warning: postpartum psychosis, depression and anxiety. A neighbour of mine had a baby about a year before me, I had met her at some local socials and said hi when we bumped into her, but I didn't know her really and I wouldn't say we were friends.(I did have her on Instagram which is relevant later) We bumped into each other more when I had my child and was going to playgroups. She was very open about her struggles with postpartum psychosis and depression both on social media and at the playgroups talking with groups of mums. At this point I hadn't experienced anything like that, so I just said that I was sorry she was going through that (again, we were never close and I didn't feel comfortable/know how to help). She then began messaging me asking if I wanted to go for walks with her, I was happy to at first. However, my husband works different shifts weekly, and she would message me every single week and become quite pushy, meaning me and my daughter spent less time with him on those days when he was around. The walks also always meant she was venting to me, telling me details of her mental health and her relationship with her husband. She would never participate in a two way conversation, if I brought an experience of my own up she would change it back to her. Now I understand that sometimes you just have to talk, but this was every week for hours and I was a brand new mum trying to figure my own new life out. I tried to distance myself and limit contact, however she quite literally lives a stone throw away from me. She can see into my house from her house it's that close. Things started to get even more tricky when I went back to work, it made finding time with my child/family/husband/other friends even more difficult and I ended up being diagnosed with late onset postpartum depression and anxiety. I started going to therapy, which happened to fall on the day she would usually want me to see her so I would tell her I had an appointment, but I didn't go into detail as I just didn't want to share it. She was also working at this point and I knew that was her only day off where she didn't have plans with her husband. I became really anxious about leaving the house on that particular day each week because I didn't want to bump into her. I didn't and still don't feel I can cope with being someone's support system when she treats me essentially as a therapist. (I know she already has a good support system with family/her husband/ actual therapist) My problem was I didn't know how to tell her as I didn't want to hurt her feeling or make things worse for her mental health. I continued to distance myself, which really wasn't all in my control because my life is extremely busy. She then messaged me to say she had taken to hospital for her mental health, I replied and said I was sorry she was dealing with this and that I hoped she got the help she needed. This is the tricky bit, she started sending me self help quotes, and I found it extremely irritating. I completely ignored her messages because I just couldn't cope with replying. I then got a message asking why I was ignoring her and if I was okay, I replied saying I needed a break from social media as I had stuff going on (not a lie- I've had a lot of difficult things going on with my family). The next day she came to my house to make sure I was okay and asked to come in, my husband had just cooked me a nice meal so I told her we would sort something for another time. I don't know what to do! I honestly wish this woman the best, I hope she gets the help she needs and can enjoy her family. I cannot be her support because I'm still trying to pull myself out of my mess. I also work, have to run my household, have little day to day support as my husband isn't home a lot and have a toddler keeping me very busy! Spending time with her is affecting my mental health so I need to do what's best for me and my family, but I don't want to upset her. Please give me an advice you have!