Anxiety from getting engaged

**long post**

Has anyone felt very anxious after being engaged?

I'm in a long term relationship (almost 7 years) and we've recently gotten engaged. For some reason ever since we've been engaged I just have an uneasy feeling, I swear it almost feels like electricity going through my body (but not in a good way). I don't know why something just feels off but I can't quite figure out what it is. When we got engaged I felt very freaked out instead of excited. I love him, he's my best friend. I'm not sure if the whole marriage thing just scares me. I deal with anxiety as well. I find myself now second guessing and over analyzing everything. I'm definitely someone who worries about everything and overthinks everything. We have some old issues that I feel like I haven't been able to move on from. I also have some emotional issues of my own (I'm going to be starting therapy soon). We will probably eventually do couples counseling in the future. I know people have told me to follow my gut and just walk away but I know my gut isn't always right. I feel like I'm scared of getting hurt. He's my first boyfriend and we've been through a lot of things that have hurt me over the years. Things have been great for the past 3 years but I have a hard time letting go of the past. Im hoping therapy will give me some clarity. Part of me is saying to walk away so that my anxiety will stop and another part of me doesn't want to. I've just been feeling emotionally overwhelmed. I also want to add that we don't live together. Has anyone ever felt a similar way?