Nervous about taking it to the next level

I've been married for 18 yrs to an abusive man. Both physically and emotionally abusive. 2 yrs ago his friend approached me and told me I deserve better than that and that he's had feelings for me since we met 17 yrs ago. We've been having an emotional affair since then. He got in some trouble and ended up in jail for 15 months. We've spoken every day since and now he's in a half way house. We both are ready to take it to the next level and be intimate. I am terrified! We love eachother and I'm leaving my husband as soon as he gets out of the halfway house. I mean I've been with the same man for 21 yrs, 18 of which we have been married. I haven't been with another man in all that time. It is scary. Does anyone have any advice or words of encouragement? I appreciate it so much. This man means a lot to me and I want our first time to be special.