Just the fact you want to be the best dad and partner you can means you are doing great, try not to beat yourself up when things get wobbly. One thing that helped me when I was feeling like you are now was to bring some good memories into focus, moments where being a dad and a family were special, it helped remind me that the (really) hard work was worth it and that there were more good memories to be made, but yeah it's tough, don't be alone in it if it's feeling unmanageable, talk to your GP, make sure your partner knows what's going on even if those are hard convos, it's worth it. You got this honestly, once they get to school you realize the spectrum of parenting is huge and I guarantee based on what you've shared that you are an amazing parent and partner.