Went on a date after being in a 3 year old relationship. Felt weird and guilty

TLDR; Went on a date after my break up and it felt weird and made me feel guilty.

So I went in my first date after being dumped, me and this girl were in a 3 year old relationship. I was absolutely crushed when she ended things.

It’s been like 2 months since the breakup. The first month I faced the break up. I cried, screamed, wrote journal, worked out etc. I still do it but not as frequent.

For the last 3 weeks I’ve felt much better and tried dating again. Yesterday I met a girl. Long story short we ended up making out, and she wanted to go all the way. But I didn’t feel like it.

After I drove her home all flashbacks of my ex kept coming at me. I felt guilty and it all felt weird, like making out with someone who is not the girl who used to be my world.

Has anybody been in a similar situation and what advice would you give? Is it normal, or am I just not over my ex yet?