Relationship Advice Required Please

My fiancée of 4 and a half amazing years recently broke up with me. We had been going through IVF the past year or two and after two failed cycles and two miscarriages, it eventually got too much for us both and we called it off. My partner said that she couldn't cope with another round, which I immediately agreed to - stated kids weren't the be all and end all, and that all I wanted in life was her. She's struggled a lot over the past few years with the miscarriages, failed cycles, alcoholism, depression and falling back on bad habits.

Recently, she told me that she was struggling and didn't want to keep falling back into the same cycles. She never really asked us to do anything, it was usually on me to suggest or fulfil her request once made. Usually we ended up watching TV/movies/playing games etc.

A few nights back, after things had been a bit tense for a few days, things like her not accepting any hugs/kisses, no longer reciprocating my "I love you so much" etc - her entire demeanor changed massively. I kinda knew something big was coming, but I didn't expect it really. We had s*x and then decided to go out for food. On the way, she told me she felt horrible. I asked why and because she said she had just used me for sex, she didn't feel any different and felt bad for "giving me hope". I was a bit broken by this. Later that evening she broke up with me, telling me it wasnt fair to keep me held on by a thread and she needed to leave and fix herself without me. She told me she couldn't bare to look at me and all she saw were miscarriages and our failed fertility journey. We both had issues, hers being incredibly low egg reserve for her age, mine being low-ish sperm count/motility, hence no natural pregnancy. (We naturally succeeded once, but miscarried)

She left to live with her friend, telling me I could keep the house and two of our cats, but she is going to collect one when she decides where to live permanently. I'm really struggling to cope with the fact she isn't here. I previously had similar traumatic breakups and it's breaking me inside that she didn't want to stay and try to make us work. Ive been messaging her since the breakup and weve been talking back and forth, she is adamant I did nothing wrong to cause it and I'm nothing but amazing, which I find really hard to believe. No matter how hard I pry for additional reasons, she assures me it is just solely her issue. She came over today to get some clothes and take some of her belongings away, we hugged for a while, cried and she apologized profusely for what she had chosen to do.

She has made it abundantly clear she has no plans to return and I, in my heart, feel she just simply doesn't love me anymore or is hopeful that with someone else she may have a chance at a family/natural pregnancy.

I really, really don't know how to cope with what has happened. I can't fathom being alone after 4.5 years almost inseparable.

Am I stupid for thinking she might come back? Should I just admit she's gone and give up, only speaking to her when she comes to collect belongings? She has said she wants to frequently come home to see the cats, but is this healthy for me? Should I leave when she comes?

I'd love to hear other people's takes on it, I can give additional information if needed, I just really, really need some help. Advice even?

I also signed myself up for therapy. I had a group session yesterday and I have another on Monday and 1-1 on Tuesday.